How to check the fuel pump
The fuel pump plays a crucial role in the fuel system of any car. The main task of the device is to supply fuel from the fuel tank to the engine. The fuel pump also regulates the amount of fuel supplied by the fuel pump reducer.
We also recommend reading the article about gas pump devices. In this article you will learn about it, what types of fuel pumps are used in gasoline cars, as well as the peculiarities of their design and principles of operation.
Petrol pump malfunction: main signs and symptoms
Productivity of electric petrol pumps, which are a mandatory element of the fuel system of injection cars and are mounted inside the fuel tank, much higher compared to mechanical fuel pumps. Mechanical pumps are installed on carburetor engines and mounted outside the fuel tank.
An implementation scheme is also possible, when there are two fuel pumps: one device will work if you need to supply a small amount of fuel under high pressure, while the second pump runs on a large amount of fuel, feeding it under reduced pressure.
It should be noted at the outset, that electric and mechanical fuel pumps supply fuel to the engine under a certain pressure. Reducing fuel pressure leads to engine malfunctions.
In the list of main features, which indicate a breakdown of the fuel pump or a clear decrease in its performance, marked:
- cold or hot engine does not start;
- there is a difficult start, unstable engine idling, floating speed;
- there are jerks and jerks of the car when you press the gas in motion when trying to accelerate;
- the car is deaf on the move;
We also recommend reading the article on tuning the fuel and air system of the engine. In this article you will learn about it, how to choose the right gas pump, injectors and other system components taking into account optimal performance.
A possible cause of these faults is low pressure in the fuel system. In other words, there is simply not enough fuel in different engine modes. To diagnose and eliminate a breakdown you need to know, how to check the pressure of the fuel pump yourself.
Check fuel and fuel pump pressure
Next we will talk about self-diagnosis of electric fuel pumps, which are installed on modern cars. There are several ways available, which allow you to check the fuel pump with your own hands.
Before starting work, the possibility of fuel leakage and reduced capacity in some parts of the fuel system should be eliminated.. Carry out a detailed inspection of fuel lines and connections for bends, cracks, other deformations or damages. The fuel filter may also need to be replaced, various gaskets, etc.. d.
In that case, if with highways and filters everything is all right, but the engine does not start, you need to turn on the ignition and listen carefully. On most cars (but not on all models) serviceable gas pump in the first seconds after turning on the ignition buzzes or emits a slight hum, injecting fuel into the system. The absence of such a sign of a working pump will indicate its malfunction or problems with electricity.
If the car starts, but then stalls on the go, then you should start the test with the fuel pump relay. To test, you need to make a connection to the fuel pump connector of the control lamp, then turn on the ignition. A warning light will illuminate for a few seconds, that the fuel pump relay is working.
How to check the fuel pressure in the fuel rail yourself
The next step will be to check the fuel pressure in the fuel system (fuel ramp). The stability of the engine when driving in different modes directly depends on the fuel pressure. You can buy a special device for such diagnostics, which is a special manometer and various adapters for connection to the fuel rail (ramps).
- The increased risk of fuel ignition should be considered before starting work, which can spill into the hood space. Precautions must be taken to minimize risks, and it is also recommended to cover the car generator and other elements under the hood with a thick cloth or other handy material.
- Then you need to release the fuel pressure in the system by turning off the fuse of the fuel pump. The specified fuse is located on the fuse panel. To accurately identify the element, it is necessary to study the operation manual of a particular car. Then you need to start the engine with the fuel pump off. The engine will stop after that, how to spend fuel residues in the system.
- The next step will be to connect the pressure gauge to the fuel rail. The connection point is often closed with a plastic cap, which needs to be unscrewed. After unscrewing the access to the special valve will open. This valve resembles a nipple, mounted on car wheels. Then the fitting must be removed. It is worth considering, that when trying to remove gasoline leaks, so you should prepare rags in advance.
- You can now connect the pressure gauge hose to the ramp, having checked reliability of its fastening. After that the manometer should be deduced through an edge of a cowl on a windshield. Next, the fuse of the fuel pump is installed in place and the engine is started. After switching on the ignition, the pressure gauge readings are recorded.
- Different car models may have different fuel pressures in the fuel system. Example, 1.6-liter VAZ injector units have a pressure in the fuel rail of about 4 atmospheres. At normal rail pressure, the pressure gauge readings should be within close range 300-380 kPa.
- Next, the car will need to accelerate to 40-50 km / h in third gear, paying attention to the readings of the manometer. At normal productivity of the petrol pump they should remain on the same mark, as when starting the engine.
Must be added, that a conventional manometer may be suitable for measuring fuel pressure, which is used to measure the air pressure in car tires. This should be taken into account, that such manometers are originally intended for high pressure measurements before 16 atmospheres, while fuel pressure gauges are limited by a limit of about 6 atmospheres. Also the air manometer can have a noticeable error.
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