Fuel Pump Pressure, Checking

Fuel Pump Pressure, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• fuel line adapter set (V.A.G. 1318/17A). These tools may be substituted with an equivalent aftermarket tool and are also available for rental or purchase through the local dealer.

• In line Fuel pressure gauge with shutoff. (high pressure).

Test conditions

• Battery voltage 12.5 V

• Function and voltage supply for the Fuel Pump is OK.

• Fuel tank at least 1/4 filled.

• Ignition switched OFF.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check

Fuel system is under pressure! Before opening the system, place rags around the connection area. Then release the pressure by carefully loosening the connection.

Start diagnosis

- Disconnect fuel supply line and catch any fuel coming out with a shop towel. Refer to the Repair Manual for location.

• Pull circlip upward to unlock fuel line

- Install a fuel pressure gauge with appropriate adapters.

- Open shut off valve on fuel gauge.

- Switch ignition on and off repeatedly until fuel pressure stops increasing pressure.

- Read fuel pressure on the gauge.

• Specified value: 3.5 to 4.3 bar

• Turn the ignition switch OFF.

If specification is exceeded:

- Check return line between fuel filter and fuel pump for kinks or blockage.

If no malfunction in fuel return line is found:

- Pressure relief valve in fuel filter is malfunctioning.

- Replace the fuel filter. Refer to the Repair Manual.

If specified value was Not obtained:

- Check fuel pressure at the fuel filter between fuel pump and fuel filter using appropriate adapters

- Open shut off valve on gauge and start the engine. Allow to idle.

- Slowly close the pressure gauge shut off and note the fuel pressure.

• Pressure must increase to 4 bar.

When 4 bar is reached: Open shut off tap immediately!

Turn the ignition switch OFF.

If pressure has increased during test:

- Fuel pump is OK. Pressure relief valve in fuel filter is malfunctioning.

- Replace the fuel filter. Refer to the Repair Manual.

If pressure did not increase:

- Fuel pump is faulty

- Replace the fuel pump. Refer to the Repair Manual.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Scan Tool Testing and Procedures.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.