Fuel Pump, Checking

Fuel Pump, Checking

Special tools, testers and auxiliary items required

• Pressure Tester (VAS 6550)

• Remote Control (V.A.G 1348/3A)

• Test Instrument Adapter/DSO (5-pin) (VAS 5565)

• Hand Held Multi-Meter (V.A.G 1526D) with Current Clamp (V.A.G 1526B/2)

• Wrench (T10202)

• Torque Wrench (40-200 Nm) (V.A.G 1332)

• Measuring Container, 2 liter

• Vehicle Diagnostic Tester

Function and Voltage Supply, Checking

• Fuel Pump (FP) relay (J17) OK

• Battery voltage at least 11.5 V.

• Fuel pump fuse OK, fuse assignment.

• FP function is checked via output Diagnostic Test Mode (DTM).

- Connect the vehicle tester as follows:





- Connect the diagnostic cable connector to the Data Link Connector (DLC) in driver's footwell.

- Turn on the ignition.

- Press the Vehicle Self-Diagnosis, Engine Electronics and Output Diagnostic Test Mode buttons on the display.

- Press the right arrow button > on the display to initiate fuel pump activation.

The fuel pump must run.

- Switch off ignition.

If FP does not start up

- Remove the rear seat bench.

- Remove the cover from the fuel delivery unit.





- Pull on the connector - arrow - without pressing the retainer to make sure it connected securely. If the connector was not connected correctly, check the fuel pump function again.





- Disconnect the connector.

- Check the contacts on the connector and the fuel delivery unit for damage.

- Connect the (VAS 5565) to the connector on the cover and on the fuel delivery unit.





- Connect a (V.A.G 1526D) to the wires - 1 and 5 - on the (VAS 5565).

- Start the output DTM again and measure the voltage at the fuel pump.

• Specified value: approximately 2 volts less than battery voltage.

Voltage Supply not OK

- Locate and repair open circuit in wiring using wiring diagram.

Voltage Supply OK

CAUTION!
Fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before loosening the connection wrap a cloth around the connection. Loosen the connection carefully to release the pressure.

- Remove the fuel lines - 1 and 2 - from the flange.





• Press in the securing ring to disengage the fuel lines.

- Remove the locking ring using (T10202).





- Check whether electrical wires between flange and FP are connected.

If No Open Circuits are Found

- Replace the fuel delivery unit if the fuel pump is faulty. Refer to => [ Fuel Delivery Unit ] Service and Repair.