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)

• Multi-meter (V.A.G 1715)

• Wrench (T10202)

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

• Measuring Container, 2 Liter

Function and Voltage Supply, Checking

Conditions

• Battery voltage at least 11.5 volts.

• Fuel pump control module (J538) fuse is OK

• Fuel pump control module is OK

Sequence

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

- Connect the vehicle diagnostic tester - 1 - as follows:





- Connect diagnostic cable - 2 - to the Data Link Connector (DLC) in the 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 until output Diagnostic Test Mode (DTM) of fuel pump electronics.

Fuel pump must now accelerate slowly up to maximum RPM.

• Fuel pump runs quietly.

- Turn off the ignition.

If the Fuel Pump Does Not Start

- Remove the rear seat bench.

- Disconnect the connector from the fuel pump control module (J538).





- Check the voltage supply between terminals - 1 and 6 - using (V.A.G 1715).





• Specified value: approximately battery voltage

Voltage Supply Not OK

- Locate and repair the open circuit in the wiring, refer to the.

Voltage Supply OK

- Remove the cover - 1 - with the fuel pump control module (J538) - 2 - from the fuel delivery unit.





- First gently pull on the connector - arrow - without pressing the retainer to make sure it is securely connected. 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.

CAUTION!
The fuel system is under pressure!

• Wear protective goggles and protective clothing to prevent injuries and contact with skin.

• Before disconnecting the connection, place a cloth around the connection. Then release pressure by carefully disconnecting the connection.

- 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 the electrical wires between the flange and fuel pump are connected.

If No Open Circuits are Found

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