Gasoline pump does not pump gasoline. Possible causes, ways to solve the problem

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Automotive fuel pump is a device designed for uninterrupted supply of fuel to an installation in which a fuel mixture is formed. Even the slightest malfunction of it leads to interruptions in the operation of the engine, and in case of more serious malfunctions, you simply do not start it.

In this article we will consider situations when the fuel pump does not pump fuel at all, or pumps, but not in the amount that the power unit needs for normal operation. We will also try to understand the possible causes of a particular malfunction of the fuel supply device and discuss methods for their self-elimination using the example of domestically produced cars of the carburetor VAZ-2109 and injection VAZ-2114.

What are petrol pumps

Cars with gasoline engines, depending on the brand, model and modification, can be equipped with fuel pumps of various designs. But they all fall into two main categories: mechanical and electrical. Most carbureted engines are equipped with mechanical fuel feeders. If you take a VAZ 2109 (carburetor), then from the factory itequipped with a diaphragm pump manufactured by DAAZ. The main difference between this device is the simplicity of the design, which is easy to understand even for a beginner. In the carburetor “nine”, the gas pump is located in the engine compartment of the car. It is easy to recognize by its characteristic hemispherical cap and fuel line hoses.

Injector VAZ 2114 engines are equipped with electric fuel pumps. Their design is also based on a membrane, but unlike the “mechanics”, the fuel supply devices in cars with automatic fuel injection are not under the hood, but directly in the tank.

Signs of a bad fuel pump

Whatever engine your car is equipped with, the signs that something is wrong with the fuel supply are similar. These include:

1. No engine response to start attempts.
2. Violation of the stability of the power unit at idle.
3. Tripling.
4. Power down.

Design of the gasoline pump of the carburetor VAZ 2109

To understand why the VAZ 2109 fuel pump (carburetor) does not pump, let's briefly consider its design. So, the “nine” fuel supply device consists of:

• body;
• pusher with mechanical paging lever;
• diaphragm assembly;
• caps with valves and fittings for attaching hoses;
• mesh filter;
• manual inflation lever.

The principle of operation of a mechanical fuel pump

Gasoline pumpdriven by a camshaft cam, which moves the pushrod in a horizontal direction, causing it to reciprocate. The pusher, in turn, acts on the mechanical pumping lever, and it already raises and lowers the membrane rod.

Thus, a certain pressure is created inside the fuel pump, which is maintained by the valves of the device cover. One of them lets fuel in without letting it back out, and the second pushes it into the fuel line leading to the carburetor.

As you can see, the design is very simple, therefore, to determine the reason that the fuel pump does not pump, it is enough to disassemble it and check the condition of the main elements.

Pusher

Since the housing does not affect the operation of the fuel pump, if it is not damaged, of course, we will start with the pusher. This element is made of steel and cannot break just like that. But wear out - please, especially if it is not original, but purchased as a separate spare part. As soon as its length decreases by a few millimeters, the fuel pump does not pump fuel.

Rather, it shakes, but the amplitude of the diaphragm movement is significantly reduced. Hence the low fuel pressure in the system, and, as a result, interruptions in the operation of the engine. The standard length of the pusher for DAAZ pumps is 84 mm. Measure its length, and if necessary, replace the worn part.

Aperture

The most common diaphragm failure is diaphragm rupture. It also happens that shedeformed. Due to this damage, the diaphragm begins to pass fuel through itself, which also causes a pressure drop in the system.

You can detect such a malfunction only by disassembling the fuel supply device. If it is the diaphragm that is to blame for the fact that the fuel pump does not pump, you will immediately see this. This problem is solved by replacing it.

Cap with valves and fittings

Since you have already dismantled the fuel pump, do not be too lazy to check the valves. One of them should let in fuel, and the other should let it out. Just blow them out and see how well they work. If the valves fail, replace the cap assembly.

Pump filter and manual priming lever

The first thing you will see when you disassemble the fuel feeder is the strainer. It is made of thin perforated plastic. The reason for the fact that the fuel pump does not pump can also be it, if it is deformed or severely contaminated.

In the first case, the filter must be replaced, in the second, it must be washed with carburetor cleaning fluid.

The manual priming lever has nothing to do with the fact that the fuel pump does not pump fuel when the camshaft rotates. The only thing that can break in it is the spring that throws it back to its original position.

Gasoline pump does not pump: injector

As already mentioned, pumps in carburetor and injection engines have a different design. In vehicles with forced fuel injection, all processes associated with itssupply to the combustion chambers are controlled by an electronic control unit, so there may be breakdowns of various kinds of electronic devices.

The main reasons why the fuel pump of an injection engine does not pump include:

• malfunction of the electric drive of the device;
• clogged pump filter;
• relay failure;
• fuse blown.

How to understand that the fuel pump is the cause of engine malfunctions

Diagnosing problems with the fuel pump in a car with an injection engine is much easier than in a car with a carbureted engine. The fact is that when the ignition is turned on, the sound of the operation of the fuel module electric motor is clearly heard. It continues for several seconds. This sound indicates that the fuel pump is turning, pumping fuel.

If this happens when the key is turned, then everything is in order with the device itself, and the cause must be sought elsewhere. Well, if when you turn on the ignition you do not hear the characteristic sound of the pump, you can be sure that the problem is in it, or in the elements of its energy supply.

Start with relay and fuse

Given that the fuel supply module is located in the tank of the car, and it is not so easy to get to it, it is better to start the diagnosis with the relay and fuse:

1. Remove the screws securing the cover of the mounting block located to the left of the steering column.
2. Under it findfuse F3 (15 A) and relay R2. These are the elements we need to check.
3. As for the fuse, it must be "ringed" with a tester. If it is unusable, replace it.

Checking the relay in a garage is quite difficult. But you can take a similar (from a neighboring socket), obviously good relay, and put it in place of the diagnosed one. Now turn on the ignition. Is the fuel pump pumping? Reason found! Well, if nothing has changed, let's move on.

Electric drive and filter

The fuel pump in the injection VAZ 2114 is an element of the fuel module, which is located in the car's tank. It also includes:

• coarse filter;
• fuel level sensor;
• pipes for connecting to the fuel line.

To get to the module, you need to remove the lower part of the rear seat, disconnect the wiring harness and unscrew the 8 screws securing its cover. Remove the entire device assembly. First of all, inspect the coarse filter. If it is clogged, replace it.

To test the motor, you will need to connect it directly to the battery terminals. In case of its normal operation, “ring” the wiring and check the ground wire contact on the module cover. If the electric motor does not show signs of life, the question "why the fuel pump does not pump" has finally found its solution.

Trying to repair it yourself is impractical. Just buy a new motor and install in place of the old one. And further,you should not spend money on buying the entire module, which now costs about 3 thousand rubles. Buy separately the electric motor and a new filter. All this will cost you three times cheaper.