Fuel Pump, Checking

Fuel Pump, Checking

Special tools, testers and auxiliary items required







- Multimeter V.A.G 1526 or Multimeter V.A.G 1715
- Adapter set V.A.G 1594 A
- Diode test lamp V.A.G 1527

Requirements







- Fuses must be OK.
- Battery voltage must be at least 11.5 V.
- All electrical consumers, e.g. lights and rear window defogger, must be switched off.

Checking function and voltage supply
- Fold rear seat bench forward.
- Remove cover under bench seat.
- Briefly operate starter. Fuel pump must be heard to run.
- Switch off ignition.

If the fuel pump does not run:
- Disconnect 4-pin connector from fuel delivery unit flange.







- Connect diode test lamp V.A.G 1527 with adapter cables from V.A.G 1594 to outer contacts of connector. LED must light up for approx. 2 seconds.

LED does not light up:
- Check activation of fuel pump relay and wiring for an open or short circuit.

LED lights up (voltage supply OK):
- Remove fuel delivery unit.
- Check that electrical wiring between flange and fuel pump is connected and has continuity.

If no open circuit can be found:
- Replace fuel delivery unit.

Checking current consumption of fuel pump
- Disconnect 4-pin connector from fuel delivery unit flange.







- Set multimeter measuring range to 20 A and connect multimeter in series between contacts - 1 - of connector and fuel pump using adapter cables from V.A.G 1594 A.

NOTE: The current pick-up clamp from multimeter V.A.G 1715 can also be connected to an adapter cable connected between connector contacts - 1 - and fuel pump.

- Connect contacts - 4 -of connector and fuel pump using adapter cables from V.A.G 1594 A.
- Start engine and run at idling speed.
- Measure current draw at fuel pump:

Specification: 3.5...4.5 amps.

If values measured lie outside specifications:
- Replace fuel delivery unit.