Delivery Pressure, Checking

Delivery Pressure, Checking

Special tools, testers and auxiliary items required

• Pressure Tester (Diesel) (VAS 6551)

• Vehicle Diagnostic Tester

Test Conditions:

• The fuses must be OK.

• Battery voltage must be at least 12 volts.

• All electrical consumers such as, for example, lights and rear window defogger, must be turned off.

- Disconnect the quick release coupling - A - (black or with a black mark) for the fuel supply line. Disconnecting the coupling. Refer to => [ Coupling, Disconnecting ] Coupling, Disconnecting.






- Connect the pressure tester (VAS 6551) to the open end of the fuel supply line using the hoses (VAS 6551/1) and (VAS 6551/2).

- Press the ON/OFF button and turn on the pressure tester (VAS 6551).

- Open the shut off valves "A" and "B" on the pressure tester and close the shut off valve "C".

- Start the engine and run at idle speed.

- Close the shut off valve "B" for a maximum of 15 seconds and read the pressure on the pressure tester (VAS 6551) :

Specified value: 0.5 bar minimum

- If the delivery pressure is interrupted occasionally, replace the fuel delivery unit.

If the specified value is achieved:

- Replace the fuel filter, if there are driveability problems.

If the specified value is not obtained:

- Remove the rear seat bench.

- Fold the carpet to the side or towards the front.

- Remove the cover from the fuel delivery unit.

• Press the lock ring to unlock the fuel line.

- Disconnect the fuel supply line, which is black or has a black mark - A - from the fuel delivery unit.






- Connect the pressure tester (VAS 6551) to the open end of the fuel supply line and the fuel delivery unit using the hoses (VAS 6551/1) and (VAS 6551/2).

- Press the ON/OFF button and turn on the pressure tester (VAS 6551).

- Open the shut off valves "A" and "B" on the pressure tester and close the shut off valve "C".

- Start the engine and run at idle speed.

- Close the shut off valve "B" for a maximum of 15 seconds and read the pressure on the pressure tester (VAS 6551) :

Specified value: 0.5 bar minimum

If the specification is again not obtained:

- Check the fuel pump delivery quantity. Refer to => [ Fuel Delivery Quantity, Checking, ] Fuel Delivery Quantity, Checking,.

• Pull on all the quick-release coupling after installing.