Gasoline does not enter the combustion chamber of the lawn mower: main reasons and solutions

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Situation: yesterday your car was driving normally, but in the morning it refuses to start. It would seem that you need to go to a car service center, but how do you actually go? Before calling a tow truck, we’ll try to figure out the problem on the spot.

Why does the engine not start (we take the following situation as a starting point: the battery is in order, the starter rotates vigorously, there is gasoline in the tank).

• There is no power to the spark plug coil (or the spark plugs do not work): unscrew the spark plug, place it on the engine body, turn the starter - there is a spark;
• Gasoline does not flow into the carburetor (we are considering exactly this type of engine; in an injection system everything is much more complicated).

There are not many elements on the path of fuel from the tank to the carburetor; their performance can be easily checked in a garage. This is not so easy to do in a parking lot, unless you “accidentally” have the appropriate set of tools lying around in your trunk.

How to check a car's fuel system

All vehicle systems are inextricably linked.
A disruption in the fuel supply, a clogged air duct, or a malfunction of the ignition system will inevitably lead to incorrect operation of the power unit. Timely diagnosis of faults and their elimination is the key to stable engine operation. The article will discuss the most common problems in the fuel supply system and methods for eliminating them. All modern cars are equipped with a fuel injection system. Thus, the fuel pump maintains a constant pressure in the fuel rail of about 6 atmospheres. The pressure at the injectors decreases slightly. Here its value fluctuates within 3 atmospheres. Of course, the given values ​​are averaged, since the fuel supply characteristic is nonlinear and varies depending on the load on the engine. Pressure fluctuations in the fuel line can be on the order of 0.2-0.4 atmospheres. Such deviations are quite acceptable and do not in any way affect the stability of the engine.

What's the result?

As you can see, if you have certain skills and knowledge, you can determine why gasoline does not flow into the engine both on engines with a carburetor and on injection power units. However, many problems can be solved yourself. For example, it is quite possible to repair, clean and adjust a carburetor in a garage. The same can be said about cleaning injectors yourself.

Finally, I would like to note that timely replacement of fuel filters, regular cleaning of the injector or carburetor, as well as driving on good quality fuel are the key to the proper operation of the power system of a gasoline or diesel engine.

Also, driving with a half-empty tank in winter leads to the active formation of condensation, which accumulates in the gas tank. As a result, condensate (water) not only settles at the bottom and enters the combustion chamber, but also causes severe corrosion of the tank walls. As a result, rust appears in the tank, and in the case of through corrosion, active fuel leaks inevitably occur.

Diagnose faults that may indicate problems with the fuel pump. Self-check of the device, measuring the pressure in the fuel rail.

How to determine why the fuel pump does not pump or works poorly. Fuel rail pressure, pump diagnostics. Wiring, relays, fuel pump fuses.

Why is it necessary to clean the fuel pump mesh? When is it better to change and how to clean the fuel pump mesh? How to properly remove the fuel pump, subtleties and nuances.

What to do if the engine is “stupid”, does not pull, and there is a deterioration in engine response after pressing the gas pedal. Basic faults, diagnostics.

The causes of whistling and increased noise during operation of the fuel pump are overheating of the pump. How to diagnose and fix the problem yourself. Tips and tricks.

Airing of the diesel fuel system: signs of malfunction and diagnostics. How to find the location of the air leak yourself, ways to solve the problem.

Pressure diagnostics

The first step in diagnosing the fuel supply system involves checking the fuel pressure in each of its individual sections under different operating modes of the power unit. In particular, by connecting a pressure gauge to the fuel rail, when you turn on the ignition, you can find out what pressure is created in it while the engine is not running. The pressure gauge readings should fluctuate between 2.8-3.3 atmospheres. When the engine is running, the pressure value will decrease slightly due to the creation of air vacuum in the throttle space. After the fuel rail, each of the injectors is checked separately. Here, not only the fuel pressure (2.7-3.1 atmospheres), but also the amount of injected fuel is subject to measurement.

If the pressure in the fuel rail or at the injectors differs from the norm, this inevitably leads to a change in the amount of fuel injected into the cylinders in one cycle, as a result of which the fuel mixture is either excessively rich or, conversely, depleted. This malfunction will not be identified by the on-board computer if the system does not provide feedback to the oxygen sensor. Deviations from the norm in the operation of the fuel supply system will inevitably lead to interruptions, “floating” speed and difficulties in starting the internal combustion engine.

For what reasons is fuel not supplied to the cylinders?

So, the general scheme of operation of the power system involves taking fuel from the gas tank, after which the fuel enters the carburetor or injector.

Next, the fuel is supplied to the intake manifold, then the fuel-air mixture enters the combustion chamber through the intake valves.

Common problems with the supply of gasoline to the internal combustion engine

• If we exclude leaks, the next reason why gasoline is not supplied to the engine is various problems with the fuel pump. Note that on cars with a carburetor there is a mechanical type fuel pump and is located in the engine compartment.

At the same time, injection engines have an electric fuel pump. This pump is located directly in the fuel tank. If we talk about a mechanical device, then often its breakdown or incorrect operation results from damage to the membranes, as well as overheating.

Let us add that if the device is not able to create the required pressure in the fuel system (no or low pressure), then the injectors on some internal combustion engines may not open, and in this case the engine will not start. In other cases, the injectors still open, but there is still not enough fuel. In this case, the unit begins to work intermittently, stalls in different modes, etc.

At the initial stage, it is necessary to measure the fuel pressure in the fuel rail of an injection engine, while at the same time not forgetting about possible problems with the pressure regulator in the rail.

• Another problem that prevents fuel from getting into the engine cylinders is dirty fuel system filters. In addition to the usual fuel filter, the injector also has a fuel pump mesh, and in the event of severe contamination of the fuel pump mesh filter, the performance of the device drops noticeably.

To avoid the above problems, filters must be changed promptly on both carburetor and injection engines. You also need to remember that the filter mesh on the fuel pump needs to be periodically cleaned or completely replaced with a new one every 50-60 thousand km. mileage

• The list of possible causes of a malfunction in the fuel supply to the engine ends with contamination of the carburetor or injection nozzles, as well as failure of individual elements. As a rule, the jets in the carburetor can become clogged, and the nozzles in the injectors are subject to contamination. Debris and deposits may also partially or completely block thin channels, etc.

To prevent this from happening, the injector must be periodically cleaned using one of the available methods (ultrasound, special cleaners on a bench, etc.). It should also be added that the carburetor may require cleaning, repair or separate tuning. For example, an insufficient amount of gasoline in the float chamber will result in insufficient fuel for normal operation of the internal combustion engine.

Checking filters

The most vulnerable components of the fuel system are fuel filters. It is their contamination that can affect the throughput of the fuel line and affect the pressure gauge readings. In addition, in the gas tank itself there are so-called “vents”, through which the tank communicates with the atmosphere. If these channels become dirty, a certain vacuum will be created in the tank, which will result in low pressure in the fuel line.

Don't forget about the filter element on the fuel pump itself. If all external filters are periodically changed, then the fuel pump, as a rule, is removed from the tank only after it fails. In addition to filter contamination, fuel pump malfunctions include failure of the check valve and oxidation of the contacts of the supply wires, due to which the electric motor ceases to develop full power. The cause of filter contamination and clogging of the fuel line is low-quality fuel with a high concentration of resins. It follows that the fuel supply system is very vulnerable, therefore, in order to avoid breakdowns, preventative maintenance should be carried out periodically.

Tank check

Naturally, the search must be carried out from the very starting point, that is, from the tank. Often the problem for beginners is that they simply ran out of gas. But there may be other problems associated with the structural components installed in the tank. Below is a picture that helps you understand what could cause the engine to stop:

Fig.1. Fuel tank:

1 – tank cover; 2 – drain plug (not present on all cars); 3 – fuel level sensor float; 4 – mesh filter element; 5 – fuel receiver.

This image shows that there is gasoline, as indicated by the sensor float. But in real life there is no such cut, and it is impossible to visually verify that there is fuel in the tank. In addition, the level sensor often “lies”, showing that there is gasoline, but in fact it has already been all used up. Therefore, you should first make sure there is gasoline. In carburetor cars this is easy to do, since there is no mesh in the neck of the tank. That is, you just need to take a thin metal rod and insert it into the tank until it stops, and then see if there is gasoline.

It is imperative to open the tank lid, and you should listen to see if there is a “sigh” from the neck. The fact is that there is a ventilation hole in the lid through which air passes into the tank. If it is clogged, then as gasoline is consumed, a vacuum forms in the tank, due to which the fuel pump cannot pump gasoline into the system. The signal that the hole is blocked is precisely a “sigh” from the neck. Sometimes it is enough to clean the lid for the power system to start working normally.

Troubleshooting the fuel injector system

How the fuel system works

Fuel is supplied to the ramp under excess pressure (about 6 atmospheres), which is created by the fuel pump. Using the pressure regulator on the nozzle, a constant pressure drop of 3 atmospheres is maintained. At constant pressure and a linear characteristic of the injectors, the amount of fuel injected is determined by the duration of the injector control pulse. This is a theory.

On a real engine, the pressure drop across the injector can range from 2.8 to 3.2 atmospheres. This is an acceptable range within which no deviations in engine operation are observed. Why is such a pressure difference possible? It is determined by the spread in the characteristics of pressure regulators.

How to check the fuel system?

Let's connect the pressure gauge to the fuel rail.
With the fuel pump turned on and the engine not running, the pressure should be 2.8-3.2 atmospheres. If the engine is idling, the pressure should drop to 2.2-2.5 atmospheres. When over-gassing, the pressure gauge needle should deviate into the zone of 2.8-3.2 atmospheres. Now let's check the operation of the injectors. With the engine not running, we will create the required pressure in the ramp (2.8-3.2 atmospheres), after which, using diagnostic equipment, we will apply a series of test pulses to the first injector, monitoring the change in pressure. The above procedure must be carried out for all injectors. The pressure drop should be the same in all cases. If the results of checking the fuel pressure correspond to those described above, the fuel supply system is working properly.

What will happen if the fuel pressure in the rail is low?

(less than 2 atm.) or increased (more than 4 atm.)? The amount of fuel injected will change in proportion to the pressure deviation from the norm. In other words, the air-fuel mixture will become lean or rich.

It will be especially painful in engine control systems without oxygen sensor feedback, since the controller does not know about the malfunction and continues to calculate the fuel supply for a normal fuel pressure value. In control systems with an oxygen sensor

the controller can compensate for changes in the composition of the air-fuel mixture, but only within reasonable limits.

If the fuel pressure is incorrect, problems arise with starting the engine, dips appear when the vehicle moves, and fuel consumption increases.

Troubleshooting the fuel system

Let us recall the composition of the fuel supply system. It includes: a fuel tank with a submersible fuel pump installed in it, a fuel filter, fuel lines (supply and drain lines), an injector ramp and a pressure regulator. Failure of any of these components may cause incorrect fuel pressure. Let's try to list the most common malfunctions for each component of the fuel supply system.

Gas tank. Through special pipelines, the gas tank communicates with the atmosphere, which prevents its deformation (flattening). If the connection with the atmosphere is broken, a vacuum is created inside the gas tank. In this case, the pressure in the fuel rail may be low.

Gasoline pump. There may be several malfunctions:

• the fuel pump does not develop the required pressure, as a result - low fuel pressure,
• the check valve of the fuel pump does not hold pressure, as a result - a rapid drop in pressure after turning off the ignition,
• contamination of the fuel pump mesh filter, as a result - reduced pump performance, which affects the dynamic operating conditions of the engine.

Fuel filter. A dirty fuel filter can lead to low fuel pressure due to reduced fuel line capacity. If the fuel filter is damaged (torn), dirt can enter the injectors with all the ensuing consequences.

Fuel lines. Fuel lines may be pinched. If this happens to the supply line, then the fuel pressure will be reduced, if it happens to the drain line, it will be increased. In addition, the use of low-quality gasoline with a high tar content can lead to a decrease in the capacity of fuel lines.

Fuel pressure control. There are regulators with a stuck diaphragm in the open or closed position. In the first case, the fuel pressure in the system will be reduced, in the second - increased.

Injectors. The following types of faults are typical:

• the injector does not open, resulting in a lean air-fuel mixture,
• the injector is constantly open, resulting in an enriched air-fuel mixture,
• the injector works, but its characteristic has “floated away”, as a result - the air-fuel mixture is incorrect.

On-board diagnostics to identify faults

A malfunction of the fuel system leads to a deviation in pressure in the fuel rail. As a result, the amount of fuel supplied to the cylinders differs from the calculated one, and the air-fuel mixture becomes depleted or enriched. In engine management systems with an oxygen sensor, the controller monitors the current composition of the air-fuel mixture.

If the air-fuel mixture deviates significantly from the desired value, the controller perceives this condition as a malfunction, and one of two fault codes is recorded in the controller’s memory:

• P0171 - fuel system too lean,
• P0172 - fuel system too rich.

High or low pressure in the fuel rail

- this is just one of the reasons why codes P0171, P0172 can be recorded in the controller’s memory. The cause of a significant depletion or enrichment of the air-fuel mixture may be faulty mass air flow sensors, oxygen sensors, or injectors. Air leaks lead to an over-lean air-fuel mixture.

The fuel pressure value may be outside the permissible range, but the on-board diagnostics does not record anything. It’s a very real situation - on-board diagnostics are not omnipotent.

A fairly common reason for the engine stopping while driving is lack of fuel. We will give examples where there was no fuel not only in the fuel tank, but also in the intake manifold. The simplest case is that there is no fuel in the tank. This situation most often occurs among young drivers. Mom and dad give their student son a car, sometimes even quite an expensive one. But, as you know, maintaining a car requires money, and quite a bit, at least you need to refuel the car. And money is allocated to my son. But the question immediately arises in the young mind: wouldn’t it be better to use this money to buy beer and hang out with friends? Since the answer is obvious, the car runs with a half-empty tank and sooner or later along the way it will stall. Second option: the young driver does not drink beer and uses the allocated money to fill up his car. But dad (or mom) allocates money based on the normal operation of the car, not taking into account that the heir can ride around the clock, if only there was someone with him. There is not enough gasoline again. Here the following should be noted: when there is little fuel in the tank, the fuel pump is forced to “grab” air along with the remaining fuel. When pumping such a mixture, all pumps, even diaphragm ones on carburetor engines, wear out very quickly and eventually fail. In addition, when the fuel level is low, the pumps collect all sorts of dirt from the bottom of the tank, which increases the likelihood of filter clogging. In other words, for young drivers, the car’s fuel system, as follows from practice, is doomed to failure. (FIG 9)

Rice. 9. Diagram of most electric fuel pumps.

1. Check valve. When it wears out, all the gasoline from the fuel rail flows back into the fuel tank within a few hours and the car has difficulty starting.
2. Safety valve. Relieves gasoline pressure if for some reason it becomes high.
3. Electric motor rear bearing.
4. Electric motor brush. It wears out much less than the collector. And when a hole appears in the commutator due to this wear, the brush warps and can become jammed in its brush holder. The motor will naturally stop.
5. Electric motor rotor.
6. Magnets glued to the body. When this magnet falls off, the electric motor either reduces its power or stops altogether.
7. Rear bearing.
8. Pump impeller. When checking the pump, if you reverse the polarity, this wheel may come loose and the motor will jam. However, if you change the polarity and lightly tap the housing, the wheel will screw back in and the motor will work as if nothing had happened.
9. Receiving filter mesh.

However, it should be noted that electric fuel pumps very rarely (in our memory, in 10 years there was only one case on a Suzuki Escudo) fail while driving, so that the engine immediately stalls.
Usually they begin to make noise and reduce performance and pressure created, but the engine continues to work, although its power may decrease. For engines with direct fuel injection, a reduction in power with a noisy electric pump will necessarily occur - this has been tested more than once. An ordinary car with gasoline injection will still work somehow with a noisy pump, but the next time it is started, its engine will not start, since the electric motor of the fuel pump will be jammed (Fig. 9). Jamming occurs because the commutator of this electric motor is worn out to holes and its brushes no longer reach the contacts of the commutator. And all because the pump had to pump dirt from the bottom of the fuel tank, while also capturing air. Diesel injection pumps also do not like dirt, air, as well as winter fuel. But if mechanically controlled fuel injection pumps somehow tolerate bad fuel (“growls”, but tolerate it), then electronically controlled fuel injection pumps cannot tolerate such a “cocktail”. On Toyota diesel engines, which have the letter “E” at the end of their name (“ephemeral”, as car mechanics say), in this case the control valve plunger becomes jammed. Sometimes before this happens, engines lose their power, start poorly and, even when overloaded, do not smoke at all. Diesel engines of Nissan, Isuzu, and Mitsubishi cars with electronically controlled fuel injection pumps will initially jerk and periodically stall, then one day they will simply not start. So, lack of fuel. A young man comes to the workshop and says: “Give me three (!) liters of gasoline, I stalled right there.” They explained to him that no one would give him gasoline here, handed him a canister (fortunately, after changing oils and coolants, there is a lot of them left in any workshop) and directed him to the nearest gas station. The young man with the canister left. An hour later, another young man appeared and said: “Right opposite your workshop, our car has stalled, start it.” Nobody wants to quit work and go out into the street (besides, they don’t know what instrument to take with them), but the boring tone and persistence of the petitioner do their job. Let's approach. On the slope there is quite a decent "

Camry" 1996, and next to it is our first visitor (a beggar for gasoline). We ask if they found gasoline. “Yes,” they answer, “it’s already filled.” Three whole liters. And this is in an empty tank, the bottom area of ​​which is about 1.5 m2, and besides, the car was placed on a slope. They explained to the young people that when the car stalls due to lack of fuel, at least 10 liters must be poured into it. Otherwise, the fuel receiver, located inside the tank in a special trough, will remain dry. When the car moves, gasoline splashes inside the tank and, even if there is little of it, splashes into this trough, from where the pump sucks it in. In this case, even three liters of fuel in the tank, splashing, will get to the fuel receiver and allow the car to drive another couple of tens of kilometers. Three liters of gasoline poured into an empty tank of a stationary car is nothing.

Another case.

They brought in
a Subaru Legacy - it stalled.
We ask if there is fuel in the tank. They answer: “Yes, the light is not on yet.” For engines with fuel injection, you can quickly find out whether there is fuel in the tank or not by pulling off the rubber return pipe and turning on the starter. Simultaneously with the starter turning on, the electric motor of the fuel pump will also start working (you can even hear it in the rear of the car). In just a second or two, the fuel pump will raise the pressure in the fuel rail, forcing the pressure reducing valve on it to operate, and a stream of gasoline will spray out of the return line. For most cars, you can remove the return line even without a tool. We do all this - there is no gasoline. We go to a gas station (the client has a cell phone, which means he is solvent), bring 20 liters of gasoline, fill it up, and the car starts. Having removed the instrument panel, we find that the emergency fuel level reduction light has burned out. We change the light bulb - the car is ready. But three or four such “repairs” and the client will have to replace the fuel pump on his Subaru. After all, before it stalls, the fuel pump is forced to pump gasoline along with air, and this, as mentioned above, wears it out very much. Let's assume that there is fuel in the tank of your car, but it still seems to you that the car will not start or stalls on the road due to a lack of fuel. Although in the latter case the car first reduces power, an attempt to press the gas pedal harder leads to the fact that the car begins to jerk and then stops altogether, but in idle mode the engine still works quite well. Diesel engines also jerk when there is a lack of fuel. In addition, the value of their revolutions cannot reach the red zone on the tachometer and gradually decreases, being limited to 3000, 2000 or 1500 rpm. It doesn't get any lower. We'll talk more about diesel cars at the end of this section, but now let's get back to gasoline cars.

Why does the car stall and not start? Perhaps this story will help you find the reason. A pickup truck came to us for repairs"

Nissan Datsun" with a Z20 gasoline carburetor engine. At idle, the engine runs flawlessly, but if you press the gas pedal while driving, the car begins to jerk and, if you do not release the gas, stalls. After 4 seconds you can start it again and continue “moving”. The first thought about the reason why the car behaves this way is that the intake mesh in the carburetor is clogged. Absolutely all carburetors have a filter mesh in front of the needle valve. She is the last line of defense against dirt. Most often, it becomes clogged with lint from the fine filter (it is made of paper, and if it is cheap, then, as a rule, it is of poor quality, and lint constantly “flies off” from the filter surface). But the owner of the car, an experienced car enthusiast, states that he cleaned the mesh in the carburetor, as well as the receiving mesh in the gas tank, replaced the fine filter, rebuilt the carburetor, checked and blew out all the gas pipes. The pump in this car, although the engine has a carburetor, like cars with fuel injection, is electric, located in the gas tank and works. There seems to be nothing to repair, and the car is clearly running low on fuel. Here we noticed that the gasoline level in the float chamber was 5-7 mm below the middle of the window. The gasoline meniscus is visible at the very bottom of the window. We removed the float to bend its tongue and set the level in the middle, but it turned out that there was nowhere to bend the tongue: it was already pressed tightly against the body of the float.

Since the fuel level in the float chamber, as is known, also depends on the fuel pressure, in carburetor engines this level must be adjusted after each change of the mechanical pump. So, maybe in our case there are problems with blood pressure? We connected a pressure gauge to the fuel hose - the pressure created by the electric fuel pump turned out to be only 0.15 kg/cm2, and for carburetors to operate, as is known, a gasoline pressure of 0.25 to 0.35 kg/cm2 is required (for most models 0.26 -0.30 kg/cm2).

We removed the gas tank, took out the pump, and put it in order. The pressure increased to 0.27 kg/cm2, and the fuel level in the sight glass rose slightly above the middle. We tried to ride it and it turned out that nothing had changed. As long as you don’t press the gas pedal, everything is fine, but as soon as you press it a little more than halfway, the car immediately starts to twitch and, if you don’t release the gas pedal, it stalls. There is no fuel level in the window anymore. We try to start the engine - there is no level, the car will not start. We pause for 3-4 seconds, turn on the starter - the fuel level appears, the engine starts, and you can drive. Until the next time you press the gas pedal. And then one of us comes up with the rather stupid idea of ​​removing and checking the fuel filter. Stupid because the filter was new. This was stated by the owner of the car, and it was visible from the filter (beautiful and shiny). We removed the filter and began to blow through it as the gasoline flowed. Based on the force with which you can blow through the fuel filter with your mouth, we usually conclude that it is working. This, of course, requires some experience, but this is a learning experience. If too much force is required to blow through the filter, the filter must be replaced.

In our case, when blowing the filter, it turned out that something was moving in it. It turned out that as a result of poor quality workmanship, the rigidity of the filter element was reduced. With a small flow of gasoline, this element held its shape, and gasoline somehow passed through it. But as soon as the flow of gasoline increased, the filter element became wrinkled. And its plastic bottom blocked the exit hole. The engine stalls. Immediately the pressure on both sides began to equalize, and after 3-4 seconds the filter element straightened, gasoline could again flow into the float chamber, and the engine started.

So, if a carburetor engine stalls when you press the gas pedal, you should check sequentially:

· fine fuel filter;

· needle valve filter mesh;

· integrity of gasoline pipelines;

· fuel pump pressure;

· cleanliness of the float chamber and the fuel level in it;

· receiving mesh in the gas tank.

It should be noted that if the ignition system is faulty, the engine also tends to stall when you press the gas pedal - a so-called “gas failure” occurs. This phenomenon is caused by the fact that it is very difficult for the ignition spark to break through the spark gap when it is filled with a rich fuel mixture, which is formed when the gas pedal is sharply pressed. But at the same time, the fuel mixture is ignited unevenly. In some cylinders the spark was able to break through the spark gap and ignite the mixture, in others it was not... All spark plugs cannot be exactly the same, some spark plug will always fail first. The engine in this situation, when accelerating, simply stalls. We call this phenomenon “fractional start”. And, as a rule, it has nothing to do with a lack of fuel. (FIG 10)

Rice. 10. You can evaluate a spark plug as follows.

• The color of the lower insulator should be sand and the same shade for all spark plugs for a given engine.
• There should be no visible signs of electrical breakdown on the upper and lower insulators.
• There should be no traces of exhaust gas breakthrough on the upper insulator at the seaming site.
• The thickness of the side electrode should be the same along its entire length.
• The gap must meet the technical requirements.

If all these tests are positive, then you can hope (just hope!) that the spark plug is working.
A complete check of the spark plug can only be done on a special stand. There are known cases when the flow of gasoline into the float chamber was limited due to deformation of the fuel tank: the owner of a microtruck jacked up his car by installing a jack under the bottom of the gas tank. As a result, the bottom bent inward and pressed closely against the gas inlet pipe. There was no receiving filter mesh on this car model, so the defect was discovered when they tried to blow through all the gas lines. The gas line to the fuel tank was blown out with your mouth by removing the gas cap to hear a gurgle, but there was none.

If your car's engine stalls and you think it may be due to lack of fuel, try pouring about one tablespoon of gasoline into the intake manifold (through the removed air pipe or air filter). If you are correct in your suspicions, the engine will start immediately. This is true for all gasoline engines: both carburetor and injection. For engines with fuel injection, we usually remove the air filter, pour gasoline directly onto it, immediately put it back in place, and then try to start the car. For carburetor engines, it is easier to supply gasoline directly to the inlet diffuser of the primary chamber (pouring it onto the air damper). It should be noted that when starting the engine with insufficient fuel supply, i.e. When starting with a lean mixture, a fuel flash in the intake manifold is possible. And if there is something to burn there, a small fire is possible. Therefore, after pouring gasoline into the intake manifold, assemble the air ducts normally and only then start the engine. In this case, even with loud bangs in the intake manifold, there will be no fire. Especially good with this “anti-fire” starting method is the ignition of engines with central injection (single-point,

TBI). Therefore, just in case, during any repair of the fuel system, keep a carbon dioxide fire extinguisher nearby.

When gasoline runs out (its flow through the injectors decreases), engines with fuel injection first reduce power, then begin to jerk (especially when driving uphill or when accelerating) and finally stall. It should be noted that if the oxygen sensor(s) in such engines are working properly, then the control unit tries to compensate for insufficient pressure in the fuel rail. Based on the signal from the sensor(s), the control unit sees that the oxygen content in the exhaust gases is too high, and immediately decides that the too lean fuel mixture needs to be brought back to normal. To do this, the computer increases (as far as it is capable) the width of all control pulses going to the fuel injectors. Therefore, the lack of gasoline in engines with injection initially manifests itself differently than in carburetor engines, but with a further decrease in fuel pressure, the control unit can no longer cope with the adjustment, the engine will still reduce power and the car will begin to twitch when accelerating, intending to stall. The jerking of the engine (and the entire car, if this happens while driving) is often accompanied by “shooting” into the intake manifold. We have a rule: if in some mode of engine operation “shooting” appears (popping noises in the intake manifold), then after checking the high-voltage wires and the ignition order, it is imperative to check the fuel system. After all, it is known that in all gasoline engines, when the mixture is too lean, a fuel flash occurs in the intake manifold.

And one more note. While the engine is cold or has not yet warmed up to operating temperature, it requires much more fuel to operate than a warm engine operating in normal mode. An increase in the amount of this fuel is ensured by wider control pulses to the injectors. And if due to some defect the fuel supply is limited, then, first of all, this will manifest itself on a cold engine. (FIG. 11)

Fuel pump of a four-wheel drive passenger car.
1 – electric pump; 2 – receiving mesh with calico weave, it is very difficult to clean it with compressed air, since it has very small cells; 3 – rheostat for fuel level sensor; 4 – ejector pump (fuel from the “return” stream also draws in fuel from the other half of the fuel tank, as a result, you can use only one electric fuel pump, although the fuel tank has two recesses); 5 – float. Kornienko Sergey Vladimirovich Vladivostok Union of Automotive Diagnostics © Legion-Avtodata

S1b › Blog › Checking the fuel system.

Hello everyone))) good article for you and me to note)

The article will describe a testing technique that does not require special devices.

From the tool you will need:

15. Replacing the fuel filter is shown here: replacing the fuel filter on Lada Priora, Kalina and Granta cars. The only difference is that after removing the filter, we direct the fuel supply hose into a plastic bottle (preferably transparent) and turn on the ignition with the key (the fuel pump turns on and fuel spills into the bottle). We inspect the condition of the fuel in the bottle. Then we install a new filter, remove the hose from the ramp and direct it into the bottle. We turn on the ignition several times and spill gasoline. We inspect the fuel in the tank again. If dirt is found after the filter, then washing the injectors is also required. We assemble the entire system and measure the pressure readings again. If the readings have not changed, then check the correct clamping of the “return” (you can try connecting a pressure gauge to the output of the regulator). If this does not help, then perhaps the blockage is serious and requires blowing with air under high pressure. It would be a good idea to check the entire pipeline from the tank for mechanical damage (dents, kinks).

16. Fuel systems without a return line are diagnosed in almost the same way. The main difference is that here the fuel regulator is located on the pump body. The fuel goes from the pump to the fine filter, and then goes to the regulator. Near the body, the fuel pipe bifurcates. One tip goes to the regulator, and the second goes to the fuel rail.

17. The main difference in the readings is the normal pressure at the ramp is 3.8 atm. When over-gassing it should jump up to 4 atmospheres. If the pressure is less, immediately check the pump. We connect a pressure gauge to the pump outlet and check the pressure. The pressure should also be at least 6 atm for a new one.

18. If the pressure is working, then check if the fuel filter is clogged. To do this, we restore the fuel line from the pump and connect to the tube suitable for the regulator. The easiest way to do this is to cut off the old tip from the fuel filter, install one end of it in a clip, and put a hose with a pressure gauge on the other. If the pressure is identical to the pump pressure, then the filter is clean. If a significant drop is visible, the filter must be replaced.

19. Next, we check the supply line to the ramp. Shut off the fuel supply to the regulator. It is easier to do this by inserting a soldered (twisted/crumpled) tip from the filter into the quick-release connection. If there is no difference here, then change the regulator. If losses are detected, then we check the entire pipeline - there may be leakage or crumpling of the pipeline, it is also possible that nozzles are leaking.

What to do if gasoline does not flow into the engine?

All work to determine and eliminate the causes is divided into 2 parts, that is, what can be done :

• in the field, with only a standard special key at hand;
• only using special tools and equipment.

In the field

If the trimmer stalls or begins to work incorrectly, and you suspect that the reason for this is a lack of fuel in the engine, then proceed as follows in the field :

1. Turn off the ignition and remove the device from your shoulder.
2. Make sure that there is fuel in the tank; if it runs out, then you have found the reason, so fill in new fuel, pump the primer and continue working.
3. If there is gasoline in the tank, then wait until the engine cools down and pump the fuel with a primer, and then carefully inspect and sniff the entire fuel system. The appearance of a wet spot or drops, as well as a sharply increased smell of fuel, indicates a malfunction that cannot be eliminated in the field.
4. If there is no gasoline leak, pump the fuel with primer by pressing it 3-5 times, then switch the trimmer to start mode and gently but firmly pull the recoil starter cable several times.
5. If this does not help, then unscrew the spark plug and make sure it is dry (a wet spark plug indicates a problem that cannot be solved in the field), pump with primer 10–15 times and switch the trimmer to start mode, 20–30 times slowly but smoothly pull the recoil starter cable. The absence of a positive result indicates a defect that can only be eliminated in a workshop, even at home.

Using special tools and equipment

To determine and then eliminate the cause, proceed from simple to complex, that is, first carry out those checks that require a minimum of equipment and effort, that is, test :

• operation of the gas distribution mechanism;
• operation of the ignition system;
• condition of the fuel and air filter.

After making sure that all the steps described above have not identified the cause of the malfunction, disassemble the fuel system, then check each part separately. If you don't know how to do this, contact a workshop.

How to check the fuel in the engine

I came across this situation, I can’t start Masha, Toyota Levin ’87. At first I thought the cover of the brain distributor was composting, changed it, it wouldn’t start, in general I thought gasoline was not getting into the engine, I found the fuel filter, unscrewed the hose, gasoline was pouring out. Then they advised me to unscrew the nut 17 on the fuel rail, there is also a hose that fits there after the fuel filter, I checked it, when I unscrewed it, there was pressure.

The question is how to check whether fuel is entering the engine itself?

because I unscrewed the old filter, and orange gasoline was running out from there, I changed the filter, now I think the MB forum or something else is clogged. Thanks everyone in advance.

Well, what about the backstory? An additive for cleaning the injector in the tank, I guess.

Unscrew the spark plugs and see if they are wet, then gasoline is coming in, if not, then...

I drove out of the garage backwards, drove out of it, the car stalled and would not start, I thought it had run out of gas, because the fuel sensor, or rather the float, was not working, the car was old, I had not changed it yet. He pushed it back. this was in August. I filled it with gas and it won't start. We checked it first, there was no spark, I sort of understood it, the distributor cap had come loose, I was looking for it for 2 months. The head is not original, but from a Toyota MP2, it seems. Found it, ordered it from Vladik. I installed it, there seems to be a spark, but it seems sluggish to me. And then every other time, I bought new spark plugs, they seemed to have a better spark, but it still wouldn’t start.

We started fuel, it probably doesn’t flow into the engine, we couldn’t unscrew the pump, since it is hidden very tightly, we need to remove the tank, unscrew the fuel filter, red liquid flowed from there, well, the gasoline is red.. Looks like a very old filter, I bought a filter from 9, It fit fine, it’s new now, they told me to check the pressure, since the fuel pump pumps pressure very strongly, if not, it means it’s leaking. how to check. When starting the car, I unscrewed some kind of nut on the fuel rail a little, and there was actually pressure there, as it was splashing in different directions. Conclusion, the pump pumps normally and gasoline reaches the fuel rail.

Now the only task is to check whether gasoline is flowing into the cylinder heads, unscrew the spark plug, place your palm in the place where the spark plug should be, and start it. nothing splashed on my palm. although I don't know if it should splash or not. So I asked the question of how to check whether there is fuel in the engine, or rather whether it is coming in or not.

I told him briefly that this has been going on since August (I can’t start the car.

Vovka2111

, did not use additives, drove exclusively on 95 gasoline, refueled at Gazprom Neft, at the intersection of cosmonauts and Popov.

Bidey

It’s not clear, they seem to be wet, and sometimes dry. sometimes there was even a cylinder of smoke, but not always. There is no smoke coming out of the exhaust.

Checking and adjusting the carburetor

One of them can be the carburetor itself, more precisely the float chamber, as well as the channels through which fuel enters it. If there is not enough gasoline in the chamber, or it simply is not pumped into it, then you should check the strainer installed under the plug (Figure 2). The check sequence is as follows: unscrew the strainer plug (2), remove the element itself (3) and wash and blow it. Then we install everything back and check its functionality.

If upon removal it is revealed that the filter is not clogged, then the reason for the non-flow of gasoline may be the sticking of the needle valve (1) installed in the float chamber cover, or the float itself (4) touching the body.

Rice. 2. Carburetor float chamber:

1 – needle valve; 2 – filter plug; 3 – mesh filter element; 4 – float.

Often during testing it turns out that gasoline is entering the chamber, but its quantity is not enough. To set the required level by bending the adjusting tongue (3), which is shown in Figure 3. When bending the tongue, you will also have to bend the float stop (2), which will allow you to adjust the needle stroke (4). After adjustment work, you should make sure that the float moves without any jamming. If it is determined that the float is full of gasoline, this indicates its breakdown, so it is better to replace the damaged element. If you don’t have a new element at hand, you can temporarily use the old one, after sealing it with epoxy glue.

Rice. 3. Adjusting the fuel level of carburetors on GAZ (a), “Zaporozhets” (b), “Moskvich” (c), VAZ “Classic” (d), ZAZ “Tavria”, VAZ-2108-09, AZLK “Aleko” ( d):

How to check without dismantling? Signs

There are several symptoms by which you can determine the malfunction of this unit:

• Jerking while moving.
• Difficulty starting the car.
• Deterioration in acceleration dynamics. The car picks up speed slowly, even if the trigger is pressed fully.

Also note that similar symptoms can occur due to malfunctions of the mass fuel flow sensor or throttle position. It would be a good idea to check and replace the filter, both gasoline and air. The resource of the latter is 10 thousand kilometers. You can determine its wear visually.

Checking the fuel supply

The simplest, but far from effective way to determine whether fuel is supplied to the carburetor is to check it manually. To do this, the inlet fitting on the carburetor is released from the fuel supply hose. Press the lever for manual pumping of gasoline several times - if fuel comes out from the removed hose, then the problem is stuck in the carburetor; if it doesn’t work, you need to contact the fuel pump.

However, manual checking is not effective

, because, firstly, it depends on the position of the damper in the air filter, and secondly, there are often situations when in manual mode everything is fine, but we start the engine - there was no fuel in the carburetor, and there is no fuel.

Testing with a bottle in this regard is a more reliable method of testing gasoline supply. To do this check, tie a plastic bottle to the removed gasoline supply hose and start the engine. This verification method gives an unambiguous answer about the location of the fault.

How to check fuel pump pressure? Methods

It happens that the element works, but does not produce the required pressure. In injection systems, injectors are very demanding on this indicator. Due to low pressure, difficulties may arise in starting the engine and failures in dynamics. How to check the fuel pump? This can be done in several ways. The first is a check at a service station. The price of such a service is about 300 rubles. However, you can check the pressure yourself. Now there are special pressure gauges for the pump on sale. But their cost reaches two thousand rubles. You can also use the ordinary one, which is used for car wheels. Every motorist has such a pressure gauge.

Checking the pump's functionality

After this, you should check whether the pump is supplying gasoline. To do this, just unscrew the clamp securing the supply pipe from the fuel pump to the carburetor, lower the end of the pipeline into a container and make sure that the pump pumps. Some fuel pumps have manual pumping, so checking is easy. But there are also pumps that do not have this function. In this case, you will have to check the operation of the unit with the starter (when the crankshaft rotates, the starter also activates the pump).

If uniform streams of gasoline come out of the nozzle, in which no air bubbles are visible, then this is an indicator of the serviceability of the gasoline pump, as well as the fuel lines leading to it. And this already narrows the circle of searches, since problems that arise in the area from the tank to the pump are eliminated.

Replace with a new one or not

If the malfunction concerns a mechanical part, the motorist has two ways to solve the problem. The first is purchasing a repair kit. It includes all the necessary parts that may break in the pump. The second is replacing the entire element with a new one. This is a more accurate and reliable method. But it is worth considering that submersible pumps are very expensive. Among the manufacturers on the market there are both originals and analogues.

No fuel is supplied to the gasoline engine: injector and carburetor

Let's start with the fact that during the operation of the car, drivers quite often encounter the fact that the engine does not start, runs intermittently, or suddenly stalls. In this case, diagnostics usually affect the ignition system (on gasoline cars) and the power system.

As practice shows, unstable operation of the power unit on gasoline cars is in many cases due to the fact that gasoline is not supplied to the engine. In this article we will talk about why this happens, as well as what the driver should do if there is no gasoline entering the engine.

Repair of diesel engine power supply system

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

The main task of the diesel engine power system is to provide the power unit with a working mixture at the right time, converting fuel energy 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 components, interconnected and responsible for each other. To avoid failures, it is necessary to carry out timely diagnostics and repair of the engine power system.

Malfunctions in the power supply system of diesel vehicles depend on:

• injection pump;
• nozzles;
• Fuel pump;
• Filters

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

1. Difficulty starting the engine;
2. Uneven operation of the internal combustion engine in any operating mode;
3. Smokiness;
4. Knocks and extraneous noise in the operation of the internal combustion engine;
5. Power reduction;
6. Increased diesel fuel consumption.

Diagnostics of the diesel engine power system begins with those components that affect diesel fuel consumption. In this way, the filters, injectors, and fuel pump are inspected.

Watch the video on how to find an air leak:

Reasons for failure of the low pressure pump:

• Using low-quality diesel fuel;
• Late maintenance;

Mechanical damage to the ceramic necks of the TNND, as a result of negligent 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 engine power system helps to avoid unexpected breakdowns on the road.

The engine is not running smoothly

Another possible option is when the engine works, but is very unstable and does not develop power.

This happened to me on a steep climb. The engine is running at high speeds in first gear, and suddenly the speed drops sharply. You tighten the choke to increase the flow of fuel into the cylinders and finish climbing the climb. The reason for this, as I think, is the smallest particles accumulated at the bottom of the float chamber, which fall into the inclined inlet with the nozzle of the primary or secondary chamber.

Source

We'll tell you and teach you

If the injection engine stops starting, you should not turn it with the starter for a long time, discharging the battery to zero.
It is better to immediately move on to troubleshooting. For stable and trouble-free operation of the engine, a certain amount of high-quality combustible mixture prepared from gasoline and air must enter its combustion chamber.

To ignite this combustible mixture, a spark discharge must appear in the combustion chamber strictly at specified time intervals.

That is why self-diagnosis of a car engine consists of checking the flow of fuel into the cylinders and the presence of an electric spark on the spark plugs.

Is fuel getting to the cylinders?

First of all, take a look at the gasoline level sensor, making sure that there is gasoline in the tank.
As funny (and sad) as it may be, there are still attempts to start the engine without fuel. If the sensor arrow shows that there is gasoline, check whether fuel is entering the combustion chamber. After turning the engine with the starter for 5-6 seconds, turn off the ignition, disconnect the high-voltage wire and unscrew the spark plug.

The wet end of the spark plug (where the side and center electrodes are located) will indicate that gasoline is entering the cylinders.

If you cannot find any remaining fuel on the spark plug, proceed to search for the link where the flow of gasoline stops.

Check if fuel is being pumped into the ramp. After turning the engine with the starter for a few seconds, turn off the ignition and quickly disconnect the inlet gasoline hose leading from the fuel tank from the fuel rail fitting.

Be careful! If the fuel pump is working, you are guaranteed to be doused with gasoline, so cover the fitting from yourself with at least the palm of your other hand. To avoid fuel ignition, do not perform this test on a hot engine.

If the engine was not going to pour fuel on you, then there is no gasoline in the fuel line or it is supplied, but under insignificant pressure.

What to do next? Check the fuel pump. It could either fail completely or not start working due to a blown fuse.

The reason for the low pressure created by the fuel pump may be severe clogging of its filter mesh or wear of the pump valves.

But what if fuel is supplied to the ramp, but does not enter the cylinders? Why don't the injectors allow gasoline to enter the combustion chamber?

Try disconnecting the wires from the throttle position sensor (TPS), located on the throttle block near the fuel rail. If the engine starts with the TPS disabled, the reason is a malfunction of this particular device.

If the engine does not start, reconnect the wires.

For monoinjection engines equipped with a single injector, a malfunction of the injector can be suspected.

On engines with distributed injection, all injectors cannot fail at the same time, and they do not work, most likely due to the lack of a command signal from the control unit.

Is there a spark?

Check for spark discharge.
After removing the high-voltage wire from one of the spark plugs, connect it to the spark gap. Using an alligator clip, securely connect the wire from the arrester body to engine ground.

Select the crocodile mounting location as far away from the engine electronic modules as possible.

Turn on the ignition and, turning the engine crankshaft with the starter, observe whether a spark appears rhythmically between the spark gap electrodes and whether it appears at all?

You can make a test spark gap yourself by cutting off the side electrode of the spark plug and soldering one end of the wire to the spark plug body and the other to an alligator clip.

If you don’t have a spark gap at hand, unscrew the spark plug, attach a high-voltage wire to it and place the spark plug on the engine away from the electronic elements so that there is reliable contact between the spark plug body and the engine ground.

Check all high voltage wires and spark plugs. If everything is in order and there is a spark discharge, but the engine does not start, check the fuel system.