Fuel Pumps, Checking

Fuel Pumps Checking

Special tools, testers and auxiliary items required

• Voltage tester (VAG 1527 B)

• Hand multi meter (VAG 1526 C) or Multi meter (VAG 1715)

• Connector test set (VAG 1594 C)

Test Conditions

• The fuses must be OK

• Battery voltage must be at least 11.5 Volts

• All electrical consumers such as, e.g. lights and rear window defroster must be switched off

Function and Voltage Supply, Checking

- Fold rear seat bench forward

- Briefly operate the starter. Fuel Pumps (FP) must run audibly.

- Switch off ignition.

If FP Does Not Start Up

Vehicles through Calender Week (CW) 47/06

Vehicles from CW 48/06.

- Cut open carpet from point - A - to point - B - in pre cut area - arrows -.





Right Side of Vehicle

- Remove cover nuts - 1 -. If necessary, backrest support - 2 - or bracket may have to be removed.





Left Side of Vehicle

- Remove bolts - 1 -.

- Then remove nuts - 2 -. Bracket will have to be pressed upward slightly to remove one of the nuts.





Vehicles from CW 48/06

- Remove rear seat bench.

Continuation for All

Check voltage supply of each individual FP as follows:

- Disconnect 4 pin harness connector from right flange of fuel delivery unit.

- Connect diode test lamp (VAG 1527 B) using adapter cables from connector test kit (VAG 1594 C) to outer terminals of connector.





- Switch on ignition, LED must light up for approximately 2 seconds.

If LED does not light up:

- Check activation of fuel pump relay and check wires for open circuit and short circuit.

LED lights up (voltage supply OK):

- Remove right FP unit. Refer to --> [ Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump ] Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump.

- Check if the electrical wiring between the flange and fuel pump is connected and has continuity.

If no open circuits are found:

- Right fuel pump is faulty. Replace fuel delivery unit. Refer to --> [ Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump ] Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump.

- Repeat test on left fuel delivery unit.

Current pick up of fuel pumps, checking

- Check current draw of each individual FP as follows:

- Connect current clamp of Multi meter (VAG 1715) to the wire of the 4 pin connector contact 1 - arrow - from wiring harness to right fuel delivery unit.





- Start the engine and run at idle speed.

- Measure FP current draw: Specified value: max. 8 amperes.

If the current draw is exceeded:

- Right fuel pump is faulty. Replace fuel delivery unit. Refer to --> [ Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump ] Fuel Delivery Unit, Fuel Gauge Sensor and Suction Jet Pump.

- Repeat test on left fuel delivery unit.