Malfunctions of the power supply system of the gasoline engine. The main malfunctions of the power system: their signs, causes, methods for detecting and eliminating. Float Chamber Fuel Level Checks

STATE BUDGET PROFESSIONAL EDUCATIONAL INSTITUTION OF THE MOSCOW REGION "RAMENSKY ROAD-BUILDING COLLEGE"

Final examination work

Profession: Car maintenance and repair master

student group: 18

FULL NAME:

Topic: Device, diagnostics, maintenance and repair of the power supply system of the carburetor engine GAZ, ZIL.

2017

1. Introduction

2. The device and principle of operation of the power supply system carburetor engine GAZ, ZIL

6. Repair of the power supply system of the carburetor engine GAZ, ZIL

1. Introduction

According to the cross-country ability, cars are divided into three groups: ordinary (road), high and high cross-country ability. The first of them (ZIL-130) are used mainly on the roads. Cross-country ability- GAZ-66 and ZIL-131 - can move on roads and off-road areas.

An engine is a machine that converts some form of energy into mechanical work. Engines in which thermal energy is converted into mechanical work are thermal.

Thermal energy is obtained by burning any fuel. An engine in which fuel burns directly inside the cylinder and the energy of the resulting gases is perceived by a piston moving in the cylinder is called a piston internal combustion engine. Such engines are mainly used in modern cars.

Consider the ZIL-130 engine:

The engine consists of a mechanism and systems that ensure its operation:

crank mechanism,

Gas distribution mechanism,

Cooling system,

Lubrication system,

Supply system.

In this paper, the power supply system of the ZIL carburetor engine is considered.

Purpose

All gasoline-powered engines have basically the same power system and run on combustible mixture consisting of fuel and air vapors. The power supply system includes devices designed for storing, cleaning and supplying fuel, air cleaning devices and a device used to prepare a combustible mixture from fuel vapor and air.

The power supply system of carbureted engines consists of a fuel tank, a sump, a fuel pump, a carburetor, an air cleaner and an inlet pipeline.

The preparation of the necessary combustible mixture from fuel and air takes place in a carburetor mounted on top of the engine on the intake pipe. The air entering the carburetor for the preparation of a combustible mixture is cleaned of dust in the air filter located directly on the carburetor or on the side of the engine. In this case air filter connected to the carburetor by a pipe.

All fuel supply devices are interconnected by metal tubes - fuel lines that are attached to the frame or body of the car, and at the transition points from the frame or body to the engine - hoses made of special grades of gasoline-resistant rubber.

The carburetor is connected to the intake ports of the head engine cylinders with the help of an inlet pipeline, and the exhaust channels are connected to the exhaust pipeline, the latter is connected to the exhaust silencer with the help of a pipe.

The K-88AM carburetor of the ZIL-130 engine has two mixing chambers, each of which serves four cylinders. When the engine is running at medium loads, fuel from the float chamber flows through the main jets, and then through the jets full power into the emulsion channels. In these channels, air is mixed with the fuel from the air jets and jets of the idle system. The resulting emulsion enters the mixing chambers through the annular slots of small diffusers. Maintaining a constant composition of the lean mixture occurs due to the deceleration of the fuel by air.

2.The device and principle of operation of the power supply system of the carburetor engine GAZ, ZIL.

2.1. The device and principle of operation of the power supply system GAZ, ZIL

The power supply system of the carburetor engine (Fig. 47) consists of a fuel tank 10, a fuel filter-sump 12, a fuel pump 1, a filter fine cleaning fuel 4, carburetor 3, air filter 2, inlet pipeline, exhaust pipeline 15, exhaust pipe 14 with exhaust silencer 13, connecting pipelines and petrol-resistant hoses 8, fuel intake valve 11;fuel level indicator in the fuel tank 9, throttle control pedal 7, control buttons for air 5 and throttle 6 carburetor dampers.

Fig.47. The power supply system of the carburetor engine.

When the engine is running, fuel from the fuel tank is forcibly supplied by the fuel pump to the carburetor float chamber, having previously been cleaned in the sediment filter and fine filter. At the same time, air pre-cleaned in the air filter enters the carburetor. In the carburetor, the fuel is mixed with air in a predetermined proportion and a combustible mixture is formed, which enters the engine cylinders through the intake pipeline, where it is compressed, ignited and burned, releasing thermal energy, which, with the help of mechanisms and systems, is converted into mechanical energy and transmitted in the form of torque to the engine. the wheels of the car, setting it in motion. Exhaust gases are discharged to the atmosphere through the exhaust pipeline.

2.2. The device and purpose of the power supply system GAZ, ZIL

Power system devices. All gasoline-powered engines have basically the same power system and operate on a combustible mixture consisting of fuel vapor and air. The power supply system includes devices designed for storing, cleaning and supplying fuel, air cleaning devices and a device used to prepare a combustible mixture from fuel vapor and air.

The fuel is placed in a fuel tank with sufficient capacity for car work during one shift. The fuel tank of the truck is located on the side of the vehicle on the frame.

From the fuel tank, the fuel enters the fuel filters-settlers, in which mechanical impurities and water are separated from the fuel. The sediment filter is located on the frame near the fuel tank. The fuel supply from the tank through the fine filter to the carburetor is carried out by a fuel pump located on the engine crankcase between the rows of cylinders on top of the engine.

The preparation of the necessary combustible mixture from fuel and air takes place in a carburetor mounted on top of the engine on the intake pipe. The air entering the carburetor to prepare the combustible mixture is cleaned of dust in the air filter located directly on the carburetor or on the side of the engine. In this case, the air filter is connected to the carburetor by a pipe.

Carburetoris connected to the inlet channels of the engine cylinder head by means of an inlet pipeline, and the exhaust channels are connected to the exhaust pipeline, the latter is connected by a pipe to the exhaust silencer.

To prevent the engine from running at an excessively high crankshaft speed, the power supply system trucks the crankshaft speed limiter is on.

The K-88AM carburetor of the ZIL-130 engine has two mixing chambers, each of which serves four cylinders. When the engine is running at medium loads, fuel from the float chamber flows through the main jets, and then through the full power jets into the emulsion channels (Fig. 19). In these channels, air is mixed with the fuel from the air jets and jets of the idle system. The resulting emulsion enters the mixing chambers through the annular slots of small diffusers. Maintaining a constant composition of the lean mixture occurs due to the deceleration of the fuel by air.

Fuel pump. On cars, the carburetor is located above the fuel tank and the fuel supply is forced. For forced supply of fuel from the tank to the carburetor, a diaphragm-type fuel pump is installed on the engine.

The pump (fig. 20) consists of three main parts! housings, heads and covers. In the housing on the axis there is a two-arm lever with a return spring and a manual pumping lever. A diaphragm is fixed between the casing and the pump head, assembled on a rod having two plates. The two-arm lever acts on the rod through a textolite thrust washer. A pressure spring is installed under the diaphragm.

The pump head has two inlet and one outlet valves. The valves have a guide rod, a rubber washer and a spring. On top of the intake valves is a strainer.

The diaphragm type fuel pump is driven directly from the camshaft eccentric.

When an eccentric or rod runs into the outer end of the two-arm lever, its inner end, moving, bends the diaphragm down and a vacuum is created above it (see Fig. 20, a). Under the action of the vacuum created, the fuel from the tank enters through the pipeline to the pump inlet and passes through the strainer to the inlet valves, while the pump pressure spring is compressed. When the protrusion of the eccentric comes off the outer end of the two-arm lever, the diaphragm moves upward under the action of the pressure spring and pressure is created in the chamber above it. Fuel is forced out through the delivery valve into the outlet channel and then through the tube into the carburetor float chamber (see Fig. 20, b).

To reduce fuel pulsation, there is an air chamber above the delivery valve. When the pump is operating, pressure is created in this chamber, due to which fuel is supplied to the carburetor evenly. The capacity of the fuel pump is designed to operate at maximum fuel flow, however, in reality, the amount of fuel supplied should be less than the capacity of the pump.

When the float chamber is filled, the needle valve closes the hole in the seat and pressure is created in the fuel line from the pump to the carburetor, which spreads into the cavity above the diaphragm. In this case, the pump diaphragm remains in the lower position, since the pressure spring cannot overcome the pressure created, and the two-arm lever swings idle under the action of the eccentric and return spring.

To fill the float chamber of the carburetor with fuel when the engine is not running, use the manual priming lever located on the side of the pump housing. The lever has a roller with a cut off part and a return spring. In the depressed position, the cut of the roller is above the rocker arm and does not affect it. When moving the manual pumping lever, the roller, with the edges of the cut-out part, presses on the inner end of the two-arm lever and moves the diaphragm down.

The manual inflation lever can be used when the eccentric has released the outer end of the two-arm lever.

Fuel filters and settling tanks . The fuel supplied to the carburetor jets should not have mechanical impurities and water, since impurities clog the holes of the jets, and water frozen in winter will cause the fuel supply to stop. To clean the fuel in the engine power system, the installation of filters and sedimentation tanks is provided. Mesh filters are installed in the filler necks of fuel tanks, in the diaphragm pump housing and in the inlet fittings of the carburetor float chamber.

On trucks, two sediment filters are additionally included in the power supply system. One of the coarse filters-settlers is installed at the fuel tank. This filter (Fig. 21, a) consists of a cover and a removable housing. Inside the housing, on racks, there is a filter element from a set of thin filter plates with stamped protrusions 0.05 mm high, so a gap of 0.05 mm wide remains between the plates. Fuel from the tank enters through the inlet into the filter sump. Since the sump has a larger volume than the fuel line, the speed of the incoming fuel is sharply reduced, which leads to the deposition of mechanical impurities and water.

Fuel, passing through the slots of the filter element, is additionally cleaned of mechanical impurities that settle on the filter element.

The fuel fine filter (Fig. 21, b) is installed in front of the carburetor. It consists of a housing, a sump cup, a filter element with a spring and a cup clamp. The filter element can be made of ceramic or fine mesh rolled up.

The fuel supplied by the diaphragm pump enters the settling glass. Part of the mechanical impurities precipitate in the settling glass, and the rest of the impurities are retained on the surface of the filter element.

Fuel coarse filter installed at the fuel tank and is designed for preliminary cleaning of the fuel entering the fuel booster pump. It consists of a housing, a sump, a cover with inlet fittings, a mesh filter element, a drain plug and an air outlet plug from the system.

Fine fuel filter designed to clean the fuel from small particles. It consists of two caps, a cover and two filter elements. At the bottom of each cap is screwed drain plug. The replaceable filter element is made of paper. The filter cap has a drain valve through which part of the fuel is drained along with the air that has entered the low pressure system.

Air filter. The car is often operated in conditions of strong air pollution. Dust, getting into the engine cylinders along with air, causes accelerated wear of both cylinders and piston rings. Purification of the air supplied for the preparation of a combustible mixture is carried out in the air filter.

On the ZIL-130 car, air filters of the inertial-oil type are used. The filter (Fig. 22) consists of an oil bath body, a cover with a pipe, a filter element made of a metal mesh or nylon fiber, a coupling screw with a wing nut.

Under the action of vacuum created by a running engine, air enters the inlet annular slot through the pipe and, moving down it, hits the oil, to which large dust particles adhere. With further movement, the air picks up oil particles and wets the filter element with it. Oil flowing from the filter element washes away dust particles that have settled on the reflector. The air passing through the filter element is completely cleaned of mechanical impurities and enters the carburetor mixing chamber through the central pipe.

The filter is installed using an adapter pipe directly on the carburetor and connected to the carburetor using an air pipe.

Fuel tank. A fuel tank is installed to store the fuel supply necessary for the operation of the car. It consists of two halves, stamped from sheet steel and connected by welding. Inside the tank, to increase rigidity and reduce fuel shock whenits movement, partitions are installed. The tank has a filler neck with a plug, in which two valves are located, the action of which is similar to the action of the steam-air valves of the radiator cap.

The fuel tank of a diesel car is similar in design to the fuel tank of a gasoline car, but there are no valves in the plug. To prevent rarefaction in the tank during fuel generation, a tube is installed from it in the upper part, which communicates the internal cavity of the tank with the atmosphere.

A fuel gauge sensor and a fitting with a tap and a suction pipe are installed on top of the tank. The intake tube at the bottom ends with a mesh filter. At the bottom of the tank there is drainer closed with a screw plug.

The capacity of the fuel tank of the car is as follows: ZIL-130-170 l.

intake pipes . The supply of a combustible mixture from the carburetor to the engine cylinders is carried out through the inlet pipeline.

The inlet pipeline of the ZIL-130 engine is cast from aluminum alloy and fixed to the heads of the right and left rows of cylinders. The intake pipeline has a complex system of channels through which the combustible mixture is supplied to the cylinders. Between the inlet channels of the inlet pipeline there is a space communicated with the cooling cavity of the cylinder heads.

Gaskets are installed to seal the junctions between the intake manifold and the cylinder heads.

Exhaust pipes . They serve to remove exhaust gases from the engine cylinders, they are made separately and attached to the outside of the cylinder heads.

To reduce the resistance to the passage of the combustible mixture and exhaust gases, the channels of the inlet and outlet pipelines are made shorter and with smooth transitions.The exhaust pipelines are sealed with metal-asbestos gaskets, and they are fixed on studs with nuts.

Heating of the combustible mixture . The process of preparing a combustible mixture does not end in the mixing chamber of the carburetor, but continues in the intake manifold and engine cylinders. For better evaporation of fuel during engine operation, the intake manifold is heated. The heating of the inlet pipeline is especially necessary when operating the car in cold weather and at the time of starting its engine. However, excessive heating of the combustible mixture is undesirable, since in this case the volume of the mixture increases, and the weight filling of the cylinders decreases.

In the ZIL-130 engine, the combustible mixture is heated due to the heat given off by the circulating liquid in the cooling cavity of the inlet pipeline. When starting these engines under conditions low temperatures heating of the inlet pipeline is possible due to the passage of hot water through the cooling system.

3. Diagnostics of the power supply system of the carburetor engine GAZ, ZIL

Diagnostic signs of malfunctions of the power system are: difficulty starting the engine, increased fuel consumption under load, a drop in engine power and overheating, a change in the composition and an increase in the toxicity of exhaust gases.

Diagnosis of the power supply system of diesel and carburetor engines is carried out by the methods of running and bench tests.

When diagnosing by the method of sea trials determine the fuel consumption when the car is moving at a constant speed on a measured horizontal section of the road with low traffic intensity in both directions.

The control fuel consumption is determined for trucks at a constant speed of 30-40 km/h and for cars - at a speed of 40-80 km/h. The amount of fuel consumed is measured by flow meters, which are used not only to diagnose the power system, but also to teach drivers how to drive economically.

Diagnosis of the vehicle's power system can be carried out simultaneously with testing the traction characteristics of the vehicle on a bench with running drums, which significantly reduces time losses and eliminates the inconvenience of the sea trial method. To do this, the car is installed on the stand in such a way that the drive wheels rest on the running drums. Before measuring fuel consumption, preheat the engine and transmission of the car for 15 minutes. at a speed of 40 km / h in direct gear and at full throttle, for which a load is created on the drive wheels by the load device of the stand. After that, for carburetor engines, the operation of the fuel pump is checked (if the stand with running drums is not equipped with a pressure gauge to control the operation of the fuel pump) with a model 527B instrument for the pressure it develops and the tightness of the carburetor float chamber valve. The pressure is measured at a low engine speed and with the shut-off valve open. The results of the check are compared with the data of the table placed on the cover of the instrument case, and, if necessary, troubleshooting is carried out.

4. Maintenance of the power supply system of the carburetor engine GAZ, ZIL

Daily Maintenance (EO):

Clean the engine of dirt;

Check the condition of the engine by external inspection and listen to its operation in different modes;

Check the fluid level in the radiator;

-check for fluid and oil leaks;

Check the oil level before starting the engine;

Visually check the tightness of the fuel lines.

Maintenance No. 1 (TO-1):

Check the fastening of the engine mounts;

Check the tightness of the connection of the cylinder head, oil pan, crankshaft oil seal;

Rinse the air filter;

Lubricate the distributor breaker shaft.

Maintenance No. 2 (TO-2):

Tighten the cylinder head nuts;

Check the gap between the valve stems and the toe of the rocker arm;

Check for fluid leakage in the entire cooling system;

Lubricate water pump bearings;

Check the fastening of the radiator and shutters;

Check water pump mounting and belt tension;

Check the operation of the steam-air valve of the radiator plug;

Replace filter elements;

Inspection to check the tightness of all devices of the lubrication system;

Drain the sediment from the oil filter;

Change the oil in the crankcase;

Check the oil level in the crankcase;

Check the operation of the fuel pump using a pressure gauge;

Check the tightness of all connections in the power system;

Check the throttle actuator;

Rinse the air filter;

Check the fuel level in the carburetor float chamber;

Clean the surface of the ignition system devices from dust and dirt and oil;

Check spark plugs and distributor breaker

5. The main malfunctions of the power supply system of the carburetor engine GAZ, ZIL

Malfunction	Cause	Solutions
No fuel supply	Clogged filters or fuel lines, malfunction of the fuel pump or carburetor.	Clean or replace filters, fuel lines Replace or repair fuel pump/carburetor
Combustible mixture lean	Reduce fuel supply or increase air intake	Increase fuel supply Restrict air intake
Rich combustible mixture	Incomplete opening of the air damper, increased fuel level in the float chamber, sticking of the float or fuel supply valve in the open position, enlargement of the holes of the jets, clogging of the air jet, leakage of the float, fuel supply valves, economizer valves.	Check and correct/adjust the air damper. Reduce fuel supply. Adjust float; adjust valves. Check tightness, seal.
Unstable engine operation	Violation engine speed adjustment. Piston sticking, actuator failure, check valve leaking, nozzle clogged, delivery valve stuck	Adjust the engine speed. Carry out the necessary engine maintenance operations.
Engine power drop	Incomplete throttle opening when the pedal is pressed all the way and clogged air filter	Adjust or replace throttle valve. Clean the air filter.
Increased fuel consumption	Flow through leaks in the fuel-line connections or a damaged fuel pump diaphragm.	Check connections (tighten if necessary). Check diaphragm (replace if necessary).

6. Repair of the power supply system of the carburetor engine GAZ, ZIL

7. Security requirements. At maintenance and car repair

All work on the maintenance and repair of the car should be carried out at specially equipped posts.

When installing the car at the service station, you should slow it down parking brake, turn off the ignition, turn on the lowest gear in the gearbox and place at least two stops under the wheels.

Before performing control and adjustment operations on a non-working engine (checking the operation of the generator, adjusting the carburetor, relay-regulator, etc.), check and fasten the cuffs of the sleeves, remove the hanging ends of the clothing, tuck the hair under the headgear, while working while sitting on fender or buffer of the machine.

A sign is posted on the steering wheel "Keep out - people are working." When removing components and parts that require great physical effort, it is necessary to use devices (pullers). During work related to turning the engine crankshaft, it is necessary to additionally check the ignition is turned off, and set the gear lever to the neutral position. When starting the engine manually, you should beware of kickbacks and use the correct grip on the starting handle (do not grab the handle, turn it from the bottom up). When using a heater Special attention refers to its serviceability, the absence of gasoline leaks; the operating heater must not be left unattended. The tap of the fuel tank of the heater is opened only during its operation; in the summer, the fuel is drained from the tank.

Do not service the transmission while the engine is running. When servicing the transmission outside the inspection ditch or overpass, it is necessary to use sunbeds (bedding). For work related to turning cardan shafts, you must additionally make sure that the ignition is turned off, put the gear lever in neutral and release the parking brake. After completing the work, re-apply the parking brake and engage a low gear in the gearbox.

When removing and setting the springs, you must first unload them by raising the frame and installing it on the goats. When removing the wheels, you should also put the car on the goats, and place stops under the unremoved wheels. It is prohibited to carry out any work on a car hung only on lifting mechanisms (jacks, hoists, etc.). Wheel disks, bricks, stones and other foreign objects must not be placed under the suspended vehicle.

The tool used in the maintenance and repair of the car must be in good working order. Hammers and files should have well-fitted wooden handles. Unscrewing and tightening nuts should be done only with serviceable wrenches of the appropriate size.

After completing all the work, before starting the engine and starting the machine, you need to make sure that all the people involved in the work are at a safe distance, and the equipment and tools are removed in their places.

Checking and testing on the go of the steering and braking systems must be carried out on an equipped site. The presence of unauthorized persons during the check of the car on the move, as well as the placement of persons participating in the check on the steps, fenders is prohibited.

When working on inspection ditches and lifting devices, the following requirements must be met:

when placing the machine on the inspection ditch (overpass), drive the machine at low speed and monitor the correct position of the wheels relative to the guide flanges of the inspection ditch; the machine placed on the inspection ditch or lifting device should be braked with a parking brake and chocks should be placed under the wheels; portable lamps in the inspection ditch can only be used with a voltage not higher than 12 V; do not smoke or light open flames under the car; do not put tools and parts on the frame, steps and other places from where they can fall on workers; before leaving the ditch (overpass), make sure that there are no people under the machine, uncleaned tools or equipment; beware of poisoning by exhaust gases and fuel vapors accumulating in the inspection ditches.

When working with gasoline, you must follow the rules for handling it. Gasoline is a highly flammable liquid that causes irritation when it comes into contact with the skin, dissolves paint well. Care should be taken when handling gasoline containers, as its vapors remaining in the container are highly flammable. Particular care should be exercised when working with ethyl rosean gasoline, which contains a potent substance - tetraethyl lead, which causes severe poisoning of the body. Do not use leaded gasoline for washing hands, parts, cleaning clothes. It is forbidden to suck up gasoline and blow out pipelines and other devices of the fuel system by mouth. You can store and transport gasoline only in closed containers with the inscription "Leaded gasoline is poisonous." Use sawdust, sand, bleach, or warm water to clean up spilled gasoline. Skin areas doused with gasoline are immediately washed with kerosene, and then with warm water and soap. Before eating, be sure to wash your hands.

Special care must be taken when handling antifreeze. This liquid contains a potent poison - ethylene glycol, the entry of which into the body leads to severe poisoning. The container in which antifreeze is stored and transported must have the inscription "Poison" and be sealed. It is strictly forbidden to pour low-freezing liquids with a hose by suction by mouth. Filling the car with antifreeze is done directly into the cooling system. Wash your hands thoroughly after servicing a cooling system filled with antifreeze. In case of accidental ingestion of antifreeze into the body, the victim must be immediately taken to a medical center for assistance.

brake fluids and their vapors can also cause poisoning if ingested, so all precautions must be taken when handling these liquids, and hands should be thoroughly washed after handling them.

Acids are stored and transported in glass bottles with ground stoppers. The bottles are installed in soft wicker baskets with wood shavings. When carrying bottles, stretchers and carts are used. Acids on contact with skin cause severe burns and destroy clothing. If acid gets on the skin, quickly wipe this area of the body and rinse with a strong stream of water.

Solvents and paints cause irritation and burns on contact with the skin, and their vapors can cause poisoning if inhaled. Car painting should be done in a well ventilated area. Wash hands thoroughly with soap and warm water after handling acids, paints and solvents.

Exhaust gases leaving the engine contain carbon monoxide, carbon dioxide and other substances that can cause severe poisoning and even death. Drivers should always remember this and take measures to prevent exhaust gas poisoning.

The engine power system devices must be properly adjusted. Periodically check the tightness of the exhaust pipe fastening nuts. When performing inspection and adjustment work related to the need to start the engine in a closed room, it is necessary to ensure the removal of gases from the muffler; performance of these works in rooms not equipped with ventilation is prohibited.

It is strictly forbidden to sleep in the cab of a car with the engine running, in such cases exhaust gases seeping into the cab often lead to fatal poisoning.

When working with a power tool, it is necessary to check the serviceability and availability of protective grounding. The voltage of portable lighting used in the maintenance and repair of vehicles should be no more than 12 V. When working with a tool powered by a voltage of 127-220 V, wear protective gloves and use a rubber mat or dry wooden platform. leaving workplace even for a short time, it is necessary to switch off the instrument. In the event of any malfunction of the power tool, grounding device or socket outlet, work must be stopped.

When mounting and dismounting tires, the following rules must be observed: mounting and dismantling of tires must be carried out on stands or a clean floor (platform), and in the field - on a spread tarpaulin or other bedding; before dismantling the tire from the wheel rim, the air from the chamber must be completely released, the dismantling of the tire adhering to the rim must be carried out on a special tire dismantling stand;it is prohibited to mount tires on faulty wheel rims, as well as to use tires that do not match the size of the wheel rim; when inflating a tire, it is necessary to use a special guard or safety devices; when performing this operation in the field, you need to put the wheel with the lock ring down.

The driver must know the causes and rules for extinguishing a fire in the park and in the car. It is necessary to monitor the serviceability of electrical equipment and the absence of fuel leakage. If the car catches fire, it should be immediately removed from the parking lot and measures should be taken to extinguish the flame. To extinguish a fire, use a thick foam or carbon dioxide fire extinguisher, sand, or cover the fire with a dense cloth. In the event of a fire, regardless of the measures taken, the fire brigade must be called.

8. List of used literature

Lack of supply is possible when the filter of the receiving pipe of the fuel tank, the fuel fine filter, the sediment filter, the fuel line are clogged, and if the fuel pump or carburetor malfunctions. V fuel pump the valves may be stuck or the diaphragm may be damaged; in the carburetor, the float or fuel supply valve may be stuck in the closed position.

When lean, the combustible mixture burns at a slower rate and burns out in the cylinder when the intake valve is already open. As a result, the engine overheats, and the flame spreads into the intake manifold and carburetor mixing chamber, which causes sharp pops. As a result, engine power decreases and fuel consumption increases.

The reasons for the formation of a rich combustible mixture can be:

Incomplete opening of the air damper;
Increased fuel level in the float chamber;
sticking of the float or fuel supply valve in the open position;
Enlargement of jet openings;
clogging of the air jet;
violation of the tightness of the float;
fuel supply valves, economizer valves.

A rich combustible mixture has a reduced burning rate and does not completely burn out in the cylinder due to a lack of oxygen. As a result, the engine overheats, and the mixture burns out in the muffler, which causes sharp pops in it and the appearance of black smoke. Prolonged operation of the engine on a rich mixture causes excessive fuel consumption and a large deposit of carbon deposits on the walls of the combustion chamber and spark plug electrodes. The power of the engine decreases, and its wear increases.

Unstable operation of the engine, in addition to these reasons, may be caused by the following circumstances. If the engine runs erratically at idle only, this may be due to a misalignment of the engine speed. If the engine stops running when the throttle is suddenly opened, this indicates possible faults accelerator pump: Piston sticking, drive failure, leaks check valve, clogged sprayer, stuck discharge valve.

The reasons for the drop in engine power, in addition to those indicated, may be incomplete opening of the throttle when the pedal is pressed all the way and clogging of the air filter.

The cause of increased fuel consumption may be fuel flowing through leaks in the fuel line connections or a damaged fuel pump diaphragm.

Lack of fuel supply, the formation of an excessively lean or rich combustible mixture are the main malfunctions of the carburetor engine power system.

Signs of a power system malfunction are as follows: inability to start or difficult starting of the engine, its unstable operation, power drop, overheating, increased consumption fuel.

The lack of supply is possible when the filter of the receiving pipe of the fuel tank, the fuel fine filter, the sediment filter, the fuel line are clogged, and if the fuel pump or carburetor malfunctions. In the fuel pump, the valves may be stuck or the diaphragm may be damaged; in the carburetor, the float or fuel supply valve may be stuck in the closed position.

A lean combustible mixture is formed either by reducing the fuel supply, or by increasing the amount of incoming air. The fuel supply may decrease for the above reasons, as well as due to a low fuel level in the float chamber, clogged jets, a carburetor strainer, wear of the fuel pump drive lever, and a decrease in the elasticity of the diaphragm spring. The air supply may increase when the air damper is not fully closed, and also due to its suction at the junctions of the carburetor components with the intake piping and the intake piping with cylinder heads.

Troubleshooting Methods

When checking the power system, first of all, it is necessary to make sure that there is no fuel leakage through the connections, since this malfunction can lead to a fire.

If there is a fuel leak or air leakage in the engine connections, tighten the fasteners, and, if necessary, replace the gaskets.

If the filter of the receiving pipe of the fuel tank, the fuel fine filter, the sediment filter and the carburetor strainer are clogged, remove the filters and their filter elements, wash them in a bath of unleaded gasoline, using a hair brush, blow compressed air and set in place. When disassembling fine filters equipped with a fragile ceramic element, it is necessary to ensure its safety. When assembling the filters, the condition of the gaskets is monitored. Damaged gaskets are replaced. Clogged fuel lines are disconnected from the fuel pump and purged with a tire pump.

The fuel pump is checked directly on the engine or by removing it from the engine. To check the pump on the engine, the fuel line is disconnected from the carburetor and its end is lowered into a transparent vessel filled with gasoline. If a strong jet of fuel comes out of the fuel line when you press the manual priming lever, the pump is working. The release of air bubbles from the fuel line indicates air leakage (leakage) in the pipeline connections or the pump.

To detect malfunctions of the fuel pump, also without removing it from the engine, a model 527B device is used, consisting of a hose with tips and a pressure gauge. The hose is connected at one end to the carburetor, the other - to the fuel line going from the pump to the carburetor. After starting the engine, the pressure gauge is used to determine the pressure created by the pump at a low crankshaft speed. For engines ZMZ-53-11 and ZIL-130, it should be 18--30 kPa. Less pressure can occur when the diaphragm spring is weakened, the pump valves are loose, or when the fuel lines and sump filter are clogged. To clarify the malfunction, the pressure drop is measured. If it exceeds 10 kPa within 30 seconds after the engine has stopped, then this is caused by a loose fit of the pump valves or the carburetor needle valve. Having connected the pressure gauge to the fuel line going to the carburetor, they start the engine and let it run on the fuel available in the carburetor float chamber until the fuel pressure is established at the previously measured level. If, even with such a connection of the pressure gauge, after stopping the engine, the pressure drop exceeds 10 kPa in 30 s, this indicates a leak in the pump valves.

To check the vacuum created by the pump, use a vacuum gauge, which is attached to the inlet fitting of the pump. Turning the crankshaft of the engine with a starter, measure the resolution, which for a serviceable pump should be 45--50 kPa. Less vacuum is due to leakage of the exhaust valve, damage to the diaphragm or gasket.

Damage to the diaphragm is evidenced by the cessation of fuel supply and its leakage from the hole in the pump housing. If the manual priming lever moves freely when the fuel supply is reduced or completely stopped, this indicates a loss of elasticity of the diaphragm spring. Finally, if the considered fuel pump malfunctions and gaps in the power system are not found, but the fuel supply is insufficient, the dimensions of the pump drive lever should be compared with the new lever, since wear of the end of the lever is possible.

In a faulty fuel pump, a damaged diaphragm, a diaphragm spring that has lost its elasticity, or a worn drive lever are replaced. If the diaphragm disks are damaged on the way, the nut of their fastening is released and, having lubricated the disks with soap, install them so that the damage points do not coincide. If the valves are not tight, the pump is disassembled, the valves are washed in gasoline and reinstalled. Worn valves are replaced.

Carburetor malfunctions that make it difficult to start the engine are detected as follows. First of all, through the window (at the K-126B carburetor) or the control hole (at the K-88A carburetor), the fuel level in the float chamber is checked. Low fuel level may be due to misadjustment or sticking of the float. A sticking of the fuel supply valve in the closed position is detected by unscrewing the carburetor drain plug. If fuel flows out of the hole for a short time and then stops flowing out, this indicates this malfunction. If you suspect clogging of the jets, unscrew the plugs and blow the jets through the holes with compressed air using a tire pump. If, after purging the jets, the engine starts to work without interruption, then the reason for the decrease in fuel supply was clogging of the jets. The clogging of the carburetor strainer is detected by removing it from the carburetor and inspecting it.

Incomplete closing of the air damper is detected when the air filter is removed. Pulling the damper control knob to failure, observe its position.

To adjust the fuel level in the float chamber of the K-126B carburetor, remove the cover of the float chamber and set the float according to the caliber. The gauge sets the distance from the plane of the body connector and the cover of the float chamber to the top point of the float. The float is set in the required position by bending the tongue resting against the end of the valve needle. The float stroke limiter is also bent, achieving a gap between the end of the needle and the tongue in the range of 1.2-1.6 mm.

To adjust the fuel level in the float chamber of the K-88A carburetor, the distance from the connector plane of the upper carburetor body to the end of the needle of the fuel supply valve is checked with a caliber. If the distance is out of range, change the number of gaskets between the valve body and the carburetor body. With an increase in the number of gaskets, the fuel level in the float chamber decreases. If adjustment in this way fails, you can carefully bend the float brackets.

If the fuel supply valve of the K-88A carburetor sticks, it is ground to the seat, and if it is impossible to achieve tightness and normal operation, the valves are replaced. The fuel supply valve of the K-126B carburetor is locked not with a needle, but with an elastic plastic washer. If the valve is leaking, replace the washer.

When checking the operation of the foot and hand drives of the throttle and air dampers of the carburetor, the following parameters are controlled. The throttle control pedal should move without jamming and friction on the cabin floor and not reach the floor when the dampers are fully opened by 3-5 mm. The gap between the clamp of the manual drive cable with throttle valves and the bracket mounted on the rod should be 2-3 mm with the button fully extended. The gap between the butt of the button manual control, the air damper drive and the cab shield with a fully open damper should be 2--3 mm.

The carburetor is adjusted to the minimum stable idle speed by a stop screw that limits the closing of the throttle valve, and screws that change the composition of the combustible mixture. When the screws are screwed in, the mixture is leaner, and when they are unscrewed, it is enriched. Before adjustment, check the serviceability of the ignition system, especially candles, and warm up the engine to a coolant temperature of 75-95 ° C.

Having stopped the engine, they turn the screws that change the composition of the combustible mixture, not tightly, but to failure, and then unscrew each screw by 2.5-3 turns. Start the engine and use the stop screw to set the position throttle valves at which the engine runs steadily. Then, wrapping or unscrewing one of the screws of the composition of the mixture with the same position of the throttle valves, they achieve the highest crankshaft speed. Do the same with the second screw. After adjusting the composition of the mixture, cover the throttle valves with the stop screw, reducing the crankshaft speed. The engine should run stably at idle at a crankshaft speed of 450-500 rpm. To check the correctness of the adjustment, gently press the throttle actuator and release it sharply. If the engine stops, then the crankshaft speed should be slightly increased by turning the stop screw and re-checking the stability of the engine. Then, in turn, the tips of the ignition wires are removed from the spark plugs of the cylinders fed by the right chamber of the carburetor, and from the spark plugs of the cylinders fed by the left chamber. For both cases, the crankshaft speed is measured with a tachometer. The difference in tachometer readings should not be more than 60 rpm.

In case of incomplete opening or closing of the throttle and air dampers, the foot drive of the throttle dampers is adjusted using a threaded fork and a rod, and a manual one with a clamp. The choke actuator is adjusted by changing the length of the cable between the control knob and the choke lever.

The power supply system must ensure the preparation of a combustible mixture of the required composition (gasoline and air ratio) and quantity, depending on the engine operating mode. From technical condition power systems depend on such performance indicators of the engine as power, throttle response, economy, ease of starting, durability.

The use of lower quality gasoline can lead to abnormal engine operation (carbon deposits, detonation, excessive fuel consumption, burnout of cylinder head gaskets, valve heads, etc.). Air filters must be in good technical condition. Violation of the tightness of the air filter housing and the integrity of the filter elements leads to an increased passage of abrasive particles.

Power system maintenance consists in a timely check of the tightness and fastening of fuel lines, pipelines for the inlet of a combustible mixture and exhaust gases, the action of the throttle and air damper drive rods of the carburetor, in checking the operation of the maximum crankshaft speed limiter once a year (in autumn), in cleaning and flushing the fuel and air filters, dismantling, washing and adjusting the carburetor twice a year (spring and autumn).

Insufficient and untimely maintenance of power supply system devices, pipelines, fuel and air supply control drives can lead to fuel leakage, fire hazard, disruption of fuel supply, re-enrichment and re-leaning of the combustible mixture, excessive fuel consumption, disruption of normal engine operation, loss of power and throttle response, difficult starting and unstable idling of the engine. Before proceeding with the removal and disassembly of the carburetor or fuel pump, you must make sure that the cause of the deterioration in the operation of the car is not defects in other components and systems, especially the electrical system.

The technical condition of the instruments and devices of the power supply system of carburetor engines is checked both with the engine not running and with the engine running.

With the engine off, check:

the amount of fuel in the tank;
the condition of the gaskets under the filler cap of the fuel tank;
fastening of the fuel tank, fuel lines, fittings and tees;
the tightness of the connections and fastening of the sediment filter, fuel pump, carburetor, air filter, intake and exhaust pipes and muffler.

With the engine running, check:

lack of fuel leakage at the junctions of fuel lines, fuel tank and carburetor;
the condition of the gaskets under the cover of the carburetor float chamber, inlet and outlet pipelines;
sump filter;
fine filter.

Malfunctions that occur in the power system in most cases lead to the formation of a lean or rich mixture. In addition to the above inspection and control work, the devices of the power supply system of carburetor engines are subjected to periodic inspection and adjustment.

TO fuel system include a fuel tank, fuel lines, a fuel pump, a fine fuel filter, sensors, a carburetor. The principle of operation of the carburetor power system is as follows (Fig. 1).

Figure 1. Schematic diagram of the carburetor power system

When the crankshaft rotates, the fuel pump starts to operate, which sucks gasoline from the tank through a strainer and pumps it into the carburetor float chamber. Before or after the pump, gasoline passes through a fine fuel filter. When the piston moves down in the cylinder, fuel flows out of the float chamber atomizer, and purified air is sucked through the air filter. In the mixing chamber, the air jet mixes with the fuel, forming a combustible mixture. The intake valve opens, and the combustible mixture enters the cylinder, where it burns out at a certain stroke. After that, the exhaust valve opens, and the combustion products enter the muffler through the pipeline, and from there they are discharged into the atmosphere.

The main malfunction of the power system gasoline engine with a carburetor is an increase in fuel consumption (a rich mixture, an increased content of CO and CH in the exhaust gases). Main reasons:

increase in the throughput of fuel jets;
reduction in the throughput of air jets;
sticking of the economizer valve, its loose closure, premature opening;
air filter contamination;
air damper does not fully open;
increase in fuel level in the float chamber.

Re-depletion of the combustible mixture, reduced content of CO and CH in the exhaust gases. Main reasons:

decrease in fuel level in the float chamber;
sticking of the needle valve of the float chamber in the upper position;
contamination of fuel jets;
low pressure developed by the fuel pump.

Engine does not run at minimum idle speed. Main reasons:

violation of the adjustment of the carburetor idle system;
clogging of the jets of the idle system;
violation of the fuel level in the float chamber;
air suction into the carburetor;
air leakage into the vacuum booster hose;
throttle valves do not return to their original position when the control pedal is in its original position;
malfunction of the forced idle economizer;
water entering the carburetor.

The engine does not increase the speed, "shots" in the carburetor. Main reasons:

poor fuel supply to the float chamber;
clogging of jets and sprayers;
the economizer valve does not open or is clogged;
air leaks through the carburetor and intake manifold leaks.

Increase in the content of CO and CH in the exhaust gases in the mode of the minimum crankshaft speed.

incorrect adjustment of the idle system;
clogging of channels and air jets of the idle system;
increase in the capacity of idle fuel jets.

Stopping the fuel supply. The main reasons are:

filter clogging;
damage to the valves or diaphragm of the fuel pump;
freezing of water in fuel lines (Fig. 2).

System ICE power supply is responsible for supplying fuel from the tank, and directing it through the cleaning elements, forming the mixture, and evenly distributing it over the engine cylinders. Malfunctions lead to disruption of the functioning of the power unit and even to its breakdown. In this article, we will analyze what breakdowns are, what is the cause, and how to repair the engine power system yourself.

The most common malfunctions in the power supply system of a gasoline engine with a carburetor are:

In order to prevent the occurrence of such problems, it is important to know what leads to this, and how to properly repair the engine power system.

Diagnostics and repair of the internal combustion engine power system

Is the power supply system of the internal combustion engine out of order? Entrust the tasks of identifying the causes of failure and troubleshooting to the masters of the Ankar technical center, and soon you will receive a serviceable car! We work with cars of any model year. We provide a guarantee for work.

Injector diagnostics by car VAZ:

Formation of a lean combustible mixture

The lean mixture has its own features: the motor overheats, temporarily loses power, “shots” appear in the carburetor.

Causes:

Low fuel pressure - less than necessary flows through the injectors;
Dirty nozzles. Occurs most often due to low-quality fuel;
Air leakage into the exhaust manifold;
A lean mixture engine loses its power significantly, this is due to the long burning of the mixture, which leads to a decrease in gas pressure in the engine cylinders. Overheating of the internal combustion engine on such a mixture also occurs.

Using the method of manually pumping fuel, you can test the operation of the system. If there are no problems with this, then it is checked for air leaks. It is necessary to start the engine and close the air damper. Then turn off the engine and carefully inspect the junction of the carburetor and exhaust pipe. If the connections are not tight enough, smudges will be visible. Eliminated by tightening the nuts.

If everything is fine with this, the system is tight, there are no smudges, the gasoline level in the float chamber is checked, if adjustment is necessary.

The jets are inspected, if clogged they are blown with air.

Violation of the composition of the mixture can lead to its excessive enrichment.

Formation of enriched fuel mixture manifests itself in the following:

Black smoke from the chimney;
Excessive consumption of gasoline;
Overheating of the internal combustion engine;
The appearance of soot in the combustion chamber.

What contributes to the formation of a rich combustible mixture:

Increased fuel pressure. The problem is either in the fuel pump or in the fuel pressure regulator, which is on the fuel rail. The opening time of the injectors remains the same, but due to the fact that the pressure increases, more fuel passes through them;
Sensor failure mass flow air;
Defective adsorber. Gasoline vapor recovery system does not work;
Injector failure. Injectors do not hold fuel under pressure, leak;
Clogged air filter;
The fuel level in the float chamber is higher than necessary;
Malfunctions in the operation of the air damper;
Diaphragm damage.

Checking and repairing the engine power system in this case is carried out by inspecting the float chamber. It is necessary to inspect the float mechanism, if there are jammings, fix the problem. Reduce the fuel level to the required level. Be sure to inspect the valve for tightness. All other problems that lead to the formation of an enriched fuel mixture can only be eliminated by repairing the carburetor.

The failure of the carburetor is one of the reasons for overspending. The cause of this problem can only be detected by inspecting and diagnosing the fuel supply elements of the engine power system.

fuel leak

Leaks appear when:

The presence of loose connections;
Damage to the fuel line;
Pump diaphragm leaks.

Leaks, especially if it is gasoline, must be eliminated immediately, this leads not only to overspending, but also to a high probability of a fire in the car.

Fuel does not enter the carburetor

Repair of the engine power system is necessary in a situation where gasoline does not reach the carburetor. This happens when the fuel cannot pass through the pipes due to the fact that the fuel lines are clogged with debris, the pump is faulty, the cleaning filters are dirty.

Checking the fuel line for blockage

The search for the cause of this, in this situation, is as follows:

The fuel supply hose is disconnected from the carburetor.
This end of the hose must be placed in a container.
Pump fuel using the manual priming lever, or crank the crankshaft with a starter.

If, as a result of these actions, the fuel does not flow with the required pressure, or does not flow at all, in this case it is necessary to clean the fuel line from debris. Or there is a malfunction in the pump.

The pump test for plausibility is best done as at least 2 times.

If, as a result of manual pumping, there is no resistance on the lever, and fuel does not flow, then the fuel pump is broken. If there is resistance, and it is significant, then the line itself is most likely clogged. This problem solved by blowing. This can be done with a special pump or compressor.

To purge the fuel line, the first step is to disconnect it from the pump, and then blow it. If this fails, even under high pressure, it will have to be replaced.

In addition to the fuel line, the fuel pickup tube with the tank strainer may be clogged. The tube must be removed and cleaned. After cleaning the line, it is recommended to rinse the tank with warm water to completely remove all contaminants.

If, as a result of the work done, the blockage was not detected or eliminated, and the fuel, as before, does not flow, it is necessary to check the pump for serviceability.

The most common problems are highlighted:

diaphragm rupture;
Failure of the diaphragm spring;
Lever wear;
Failure of the springs holding the valves;
Damage to the fuel pump housing.

Diagnosis begins with a visual inspection. The first step is to check if there are any fuel leaks. They can appear if there is damage to the case, leaky connections, breakage of the diaphragm.

If smudges are found at the junctions of the pipes and parts of the pump, then you need to tighten the nuts. Next, the cover is removed and the mesh filter is cleaned.

If the diaphragms fail, there will be smudges through the lower hole in the housing, respectively, increased fuel consumption, an increase in pressure and oil level. It is worth considering that with such malfunctions, the fuel pump will continue to work. Broken diaphragms cannot be repaired, they must be replaced with new ones.

Inspection of the carburetor strainer

In a situation where fuel line is not contaminated, the pump is working properly, the strainer is being checked. If necessary, clean and blow it with air.

The reliability of the carburetor is achieved by:

Regular cleaning and rinsing;
Regular tightness checks;

To repair the carburetor, you must first dismantle it. This is followed by disassembly and cleaning. All parts are blown with compressed air. Damaged parts must be replaced. Then the carburetor is assembled and mounted in its place.

There are situations when it is possible to troubleshoot the carburetor without removing it from the car. However, he does not fully understand.

In cars equipped with a diesel engine, the power system functions quite differently than in carburetor cars. Its job is to supply air and the necessary portions of fuel to the cylinders of the power unit.

The main task of the power system diesel engines is to provide the power unit with the working mixture at the right time, converting the energy of the fuel into mechanical energy. Unlike the power supply system of a carburetor engine, the formation of a combustible fuel mixture occurs in the cylinder itself. Air and fuel are supplied separately.

The power supply of diesel engines consists of a large number of nodes that are interconnected and responsible for each other. To avoid failures, it is necessary to carry out timely diagnostics and repair of the engine power system.

Troubleshooting in power system diesel vehicles depends on:

injection pump;
injectors;
fuel pump;
Filters.

Based on the statistics of our car service, most malfunctions occur in mechanisms that operate under high pressure.

Symptoms of a fuel system problem:

Difficult start of the motor;
Uneven operation of the internal combustion engine in any operating mode;
Smokeiness;
Knocks and extraneous noise in the operation of the internal combustion engine;
Power reduction;
Increase in solar consumption.

Power system diagnostics diesel engine starts with those nodes that affect the flow diesel fuel. Thus, the filters, nozzles, fuel pump are inspected.

Watch the video on how to find the air leak:

Causes of failure of the low pressure pump:

The use of low-quality diesel fuel;
Untimely maintenance;

Mechanical damage to the ceramic necks of low pressure fuel pumps, as a result of careless handling, leads to its failure and restoration is no longer possible. In such a situation, only replacement is possible.

Timely maintenance and repair of the motor power system helps to avoid unforeseen breakdowns on the road.

Regular maintenance will help avoid unexpected breakdowns. maintenance consists in the following:

Inspection of joints, checking for tightness;
Every 10-15 thousand km:
- Washing the coarse filter and replacing filter elements;
- Checking the oil level in the injection pump;
Every 100 thousand km, check and adjust the injection pump;
Change the air filter once a year.
Every 20 thousand km, the carburetor is cleaned and its operation is checked.

In conclusion…

Repair of the engine power system is an important and responsible process. We recommend entrusting such a task to specialists who have the necessary knowledge and modern tools. Masters of the auto technical center "Ankar" with high quality will carry out diagnostics and repair of the power supply system of both gasoline and diesel engines of cars of any make and model year.

We employ specialists who have many years of experience in the repair of engine power systems. Malfunctions lead to disruption ICE operation, increase fuel consumption and reduce the level of safety, your car just at one moment may not start.

Malfunction (sign)	Causes	Remedy
Engine won't start	Lack of fuel in the tank. Clogged fuel lines. Clogged fuel filters. Fuel pump malfunction: Diaphragm damage Clogged valves Clogged strainer. Carburetor malfunction: Fuel level mismatch in float chamber Needle valve stuck closed Clogged jets	Fill with fuel. Blow out the fuel lines. Rinse filters. Replace diaphragm. Rinse valves. Rinse filter. Check and adjust float position. Flush the valve, remove the jam. Blow out the jets
The engine does not develop full power	Air cleaner clogged. Incomplete opening of the throttle valves of the carburetor. Fuel pump malfunction. Carburetor malfunction	Clean or replace filter element. Adjust throttle actuator. Check pump operation and replace worn parts. Check and adjust the position of the float, blow out the jets, adjust the damper actuators
Smoky exhaust	Insufficient air supply. Incomplete opening of the carburetor air damper. Carburetor misadjustment (very rich mixture)	Clean or replace filter element. Adjust the air damper actuator. Adjust carburetor

Diagnosis of the power supply system of the carburetor engine. When diagnosing the power supply system of a carburetor engine, the following indicators are determined and checked.

1. Tightness of the system (visual control).

2. The quality of the fuel pump. The fuel pump is checked directly on the engine or by removing it from the engine. To check the pump on the engine, the fuel line is disconnected from the carburetor and its end is lowered into a transparent vessel filled with gasoline. If a strong jet of fuel comes out of the fuel line when you press the manual priming lever, the pump is working. The exit of air bubbles from the fuel line indicates air leakage (leakage) in the fuel line connections or the pump. Damage to the diaphragm is indicated by the cessation of fuel supply and its leakage from the hole in the pump housing. If the manual priming lever moves freely when the fuel supply is reduced or completely stopped, this indicates a loss of elasticity of the diaphragm spring.

To detect pump malfunctions, special devices are also used, consisting of a hose with tips and a pressure gauge. The device is connected to the system between the pump and the carburetor, the engine starts and the pressure generated by the pump is measured. Based on the pressure value and pressure drop, malfunctions of the pump and other devices of the system are determined (weakening of the diaphragm spring, loose fitting of the pump valves, clogging of fuel lines and filters). To check the vacuum created by the pump, a vacuum gauge is used, which is attached to the inlet fitting of the pump. If the vacuum value is lower than the nominal value, this indicates a leak in the exhaust valve, damage to the diaphragm or gasket.

3. The fuel level in the carburetor float chamber is checked in various ways (depending on design features carburetor): according to the risks of the viewing window; along the edge of the control hole with a stopper; a special device that works on the principle of communicating vessels.

4. Tightness of float and needle valve. The tightness of the float is checked by immersing it in water heated to 80 ° C and observing it for at least 30 s. Air bubbles will appear from a leaky float. Checking the tightness of the needle valve with sufficient accuracy can be performed on the carburetor removed from the engine or separately on its cover using a rubber bulb. If, after creating a vacuum in the fitting with a pear for 15 s, the shape of the crumpled pear has not changed, then the tightness of the valve can be considered sufficient. In this case, it is necessary to ensure that the float presses on the valve, moving it all the way into the seat. A more accurate check is made using a special vacuum device.

5. The throughput of the jets is checked with special devices (Fig. 73a). The amount of water flowing through the metering hole of the jet for 1 min under a certain pressure (1000 mm of water column) at a water temperature of 19 ... 21 ° C will be the throughput of the jet, which must correspond to the nominal value.

For a comprehensive check of carburetors, special stands are used that allow you to measure almost all the main parameters of the carburetor: the tightness of the needle valve, the fuel level in the float chamber, the performance and performance of the accelerator pump; throughput of jets (Fig. 73b). These stands also allow you to check carburetors and fuel pumps both separately and simultaneously.

6. The performance of the accelerator pump. To check the accelerator pump, the carburetor is removed from the engine, the float chamber is filled with gasoline and a container is placed under the opening of the carburetor mixing chamber. By pressing on the accelerator pump rod, 10 full piston strokes are made. The amount of gasoline leaked into the container is measured with a beaker and compared with the nominal value.

Rice. 73. A device for checking the throughput of jets (a) and a stand for checking carburetors and gasoline pumps (b): 1 - reservoir; 2 - supply valve; 3 - drain tube; 4 - pressure tube; 5 - checked jet; 6 - beaker

7. The toxicity of exhaust gases is checked at idle using a gas analyzer (Fig. 74).

Rice. 74. Automotive gas analyzers

Before taking measurements, the engine must run for less than 1 minute in test mode. The sampler is inserted into the outlet pipe to a depth of 300 mm from its cut. The gas is sucked in by means of a pump located in the device case, passes through the filter and enters the measurement unit. The analysis of gases is carried out at a minimum stable idle speed of the crankshaft and at a speed equal to 60% of the nominal. The CO content during such measurements should not exceed the established values.

Repair and adjustment of the power supply system of the carburetor engine. Adjusting the fuel level in the float chamber carried out by changing the number of gaskets between the needle valve body and the carburetor body or by carefully bending the tongue 8 or the float bracket (Fig. 75). In this case, the bearing surface of the tongue must be perpendicular to the axis of the needle valve and must not have notches and dents.

The distance between the float and gasket 10 adjacent to the carburetor cover (dimension A) must comply with the standard established for this carburetor. The control of this distance is performed by a caliber. In this case, the carburetor cover should be held vertically so that the float tongue 8 lightly touches the ball 5 of the needle valve 4 without sinking it.

The value of the maximum stroke of the float is adjusted by bending the stop 3. The pulling fork 6 of the needle valve should not interfere with the free movement of the float. When installing the carburetor cover, it is necessary to check whether the float touches the walls of the float chamber. The fuel level necessary for the normal operation of the carburetor provides only correct installation serviceable elements of the locking device (needle valve).

Rice. 75. Checking and adjusting the fuel level in the carburetor float chamber: 1 - carburetor cover; 2 - needle valve seat; 3 - emphasis; 4 - needle valve; 5 – a ball of a locking needle; 6 - draw fork of the valve needle; 7 - float bracket; 8 - tongue; 9 - float; 10 - gasket

Carburetor adjustment carried out during the period of engine idling (warmed engine with working system ignition). When adjusting the carburetor with sequential opening of the throttle valves (used for engines cars) with the throttle stop screw (quantity screw) they tend to reduce the crankshaft speed, and with the mixture quality screw - to maximize it. The disadvantage of this adjustment is that the quality screw enriches the mixture, i.e. in the exhaust gases, the content of CO increases, which may exceed the established norms.

Therefore, the idle system must be adjusted using a gas analyzer. The quality screw sets the recommended for this engine the crankshaft speed (according to the tachometer) at idle and after 10 ... 30 s, the CO content in the exhaust gases is fixed, after which the quality screw is carefully turned 1/2 turn, then 1/4 turn, until the CO content decreases to the required value . Next, use the quantity screw to restore the crankshaft speed to the recommended one. If it turns out that the CO content again exceeded the norm or the engine began to work unstably due to the depletion of the mixture, then all operations are repeated, simultaneously achieving the required speed and the required CO content.

For truck engines, parallel-throttle carburetors with two quality screws are used. Their adjustment is carried out in the following sequence: set the recommended by the factory frequency of rotation of the crankshaft (according to the tachometer) with the quantity screw; one of the quality screws leans the mixture before the start of uneven engine operation; slowly (in several stages) by turning another quality screw, set the CO content in the exhaust gases below normal; turning the first quality screw, bring the speed to normal (the CO content in the exhaust gases should be below the standard mark). If necessary, adjust the second quality screw.

After the adjustment of the idling system is completed, the throttle response of a well-heated engine is checked by both slow and fast opening of the throttles, as well as when the car is moving during sharp acceleration. At the moment of transition from idling to work with a load in the carburetor, there should be no interruptions, "failures" or pops.

Malfunctions of the devices of the power supply system of the carburetor engine and methods for their elimination. If such malfunctions as fuel leakage or air leakage in the power system connections are established, tighten the fasteners or replace the gaskets. Clogging of the filter of the receiving tube of the fuel tank, fine and coarse filters and the carburetor strainer requires the removal of filters and their filter elements. They are replaced with new ones, and in some cases they are washed in a bath of unleaded gasoline, using a hair brush, blown with compressed air and installed in place. When assembling the filters, the condition of the gaskets is monitored. Damaged gaskets are replaced. Clogged fuel lines are disconnected from the fuel pump and purged with a tire pump.

In a faulty fuel pump, a damaged diaphragm, a diaphragm spring that has lost its elasticity, or a worn drive lever are replaced. If the diaphragm disks are damaged on the way, the fastening nut is released and, having lubricated the disks with soap, install them so that the damage points do not coincide. If the valves are leaking, the pump is disassembled, the valves are washed in gasoline and reinstalled. Worn valves are replaced.

When disassembling the carburetor, care must be taken not to damage the gaskets and parts. Jets, valves, needles and channels are washed with clean kerosene or unleaded gasoline. After washing, the jets and channels in the carburetor body are blown with compressed air. To clean jets, channels and holes, do not use hard wire or any metal objects. It is also not allowed to blow compressed air through the assembled carburetor through the inlet fitting and balancing hole, as this leads to damage to the float. To clean the parts of the carburetor from resins, they must be put into a solvent (acetone, benzene) for several minutes, and then thoroughly wiped with a clean rag soaked in the solvent. With an increase (as a result of wear) of the flow sections of the jets, they are replaced.