Notes on fuel pressure check (reference pressure: ambient pressure)

13 31 …

The feature of this embodiment to ambient pressure as the reference:

Vacuum hose fuel pressure regulator is connected between the throttle valve and air filter or the air filter.

Pre-test conditions:

Installed the required fuel pressure regulator.

– With the help of ETK verify compliance with the established in the pressure regulator car:

Connect a test adapter.


The pressure regulator must reliably fulfill their function in all operating modes. The fuel pump should always provide a higher pressure than that which sets the pressure regulator.

The dosage amount of the fuel injection control is carried out injection duration; Injection is regulated by the length of DME system.

Description of functioning: fuel return line

With the engine stopped and the ignition key position 0 in the return fuel line located behind the controller, there is no pressure.

Functional description: The pressure lock function

With the engine stopped and the ignition key position 0 pressure regulator is closed. The fuel feed pressure in the fuel feed line is maintained for a long time. The fuel pump check valve closes. These measures supported by the fuel pressure in the fuel system. This prevents the increase start time.

Complaint: Violation of the engine dynamics, lack of power

– Run the engine at idle speed and measure fuel pressure.

If the measured value is less than the nominal value – 0.2 bar:

– Narrowed cross section of the supply of the fuel, or the fuel filter is clogged,


– Supplying the fuel pump supply circuit is not in order, for example, due to the large transient resistance (corrosion) in plug connection between wiring harness and fuel pump

If the measured value is greater than the nominal value + 0.2 bar:

– Switch off the engine and observe the measured value.

– If it is reduced to the nominal value, then narrowed or clogged fuel return lines.

– Check the fuel lines for lack of fractures.

In the absence of fractures:

– Replace return lines.

If the measurement is too high, then a high degree of probability of faulty pressure regulator.

A warning:

To a lesser extent there is a possibility of complete overlap of the return conduit due to clogging. In this case, removing the pressure regulator under pressure should the fuel leak!

– Prepare rags, acting collect fuel and dispose of.

– Replace the pressure regulator is not, as the return line.

Complaint: Difficulty starting

– Allow the engine to run for a while at idle and drown.

– Remove and record the reading with the engine off.

– After about 20 – 30 minutes again to take readings with the engine off.

For the next test will need special tool 13 3 010 (hose clamp).

If the measured value has fallen more than 0.5 bar:

– Start the engine and wait a constant discharge pressure

– Stop the engine and use the special tool 13 3 010 immediately pinch the supply hose directly to the pressure gauge.

– The measured value is recorded.

– After about 20 – 30 minutes again to take readings with the engine off.

If the measured value is now dropped by less than 0.5 bar, it can be assumed the following faults:

– Faulty supply lines

– Malfunction of the supply hose inside the fuel tank

– Faulty pressure lock valve (check valve) in the fuel pump

Check the details. Replace defective parts.

If the measured value has fallen again by more than 0.5 bar:

– Replace the pressure regulator.


– All fuel pipes and clamps, which were disconnected to check should be replaced.

– Read fault memory of DME control unit. Check stored fault messages. Rectify faults. Erase fault memory.