Transfer Fuel Pump G6, Checking
Transfer Fuel Pump G6, Checking
=> [ Fuel Delivery, Checking ]
=> [ Voltage Supply, Checking ]
=> [ Current Draw, Checking ]
Special tools, testers and auxiliary items required
• Vehicle Diagnostic Tester, for example; Vehicle Diagnosis, Testing and Information System (VAS 5051 B)
• Test Instrument Adapter/DSO (5-pin) (VAS 5565)
• Current Pickup (V.A.G 1526 B/2)
• Handheld Multi-Meter (V.A.G 1526 D)
• Pressure Tester (VAS 6550)
• Measuring Container (3 Liter)
• Observe the safety precautions when working on the fuel supply system. Refer to => [ Safety Precautions ] Fuel Supply.
• Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Fuel Supply.
Always follow these instructions before and during work.
Fuel Delivery, Checking
Test Conditions
• The battery voltage must be at least 12 volts.
• The fuses must be OK.
• All electrical consumers such as, for example, lights and rear window defogger, must be turned off.
Test Sequence
- Disconnect the connector - 1 - from the auxiliary fuel pump.
- Disconnect the black fuel supply line - A - from the fuel tank.
- Connect the pressure tester (VAS 6550) to the fuel supply line - A - on the fuel tank.
- Guide the open end of the hose from the pressure tester (VAS 6550) into a measuring container.
- Open the shut off levers in the direction of flow before and after the manometer and close the lower shut off lever.
- Connect the vehicle diagnostic tester - 1 - as follows:
- Connect the diagnostic cable - 2 - to the Data Link Connector (DLC) in the driver's foot well.
- Turn on the ignition.
- Perform the guided function "Check Electric Fuel Pumps".
• The fuel pump now runs for 60 seconds.
- By carefully closing the shut off lever behind the manometer, adjust the pressure to 0.5 bar.
- Stop the vehicle diagnostic tester test sequence if necessary and empty the measuring container.
- Guide the open end of the hose from the pressure tester (VAS 6550) back into the measuring container.
- Start the guided function "Check Electric Fuel Pumps" again.
• The fuel pump now runs for 60 seconds.
- Turn off the ignition.
- Read the quantity of fuel in the measuring container.
Specified Values
• Minimum 1950 ml/60 seconds
• Maximum 2750 ml/60 seconds
If the quantity of fuel delivered is less than the specified value:
- Check the fuel pump voltage supply, refer to => [ Voltage Supply, Checking ] and the current draw. Refer to => [ Current Draw, Checking ].
Voltage Supply, Checking
Test Conditions
• The battery voltage must be at least 12 volts.
• The fuses must be OK.
• All electrical consumers such as, for example, lights and rear window defogger, must be turned off.
Test Sequence
- Remove the rear seat bench.
- Remove the cover - 1 - for the fuel delivery unit. The arrow - 2 - points in direction of travel.
- Turn on the ignition.
• The transfer fuel pump must run audibly for approximately 2 seconds.
• The transfer fuel pump runs quietly.
- Turn off the ignition.
If the transfer fuel pump does not run:
- Disconnect the connector - 1 - from the fuel delivery unit flange.
- Connect the test instrument adapter/DSO (5-pin) (VAS 5565) between the connectors on the flange and cover.
- Connect the handheld multi-meter (V.A.G 1526 D) to the test contacts - 1 and 5 - on the test instrument adapter/DSO (5-pin) (VAS 5565).
- Connect the vehicle diagnostic tester - 1 - as follows:
- Connect the diagnostic cable - 2 - to the Data Link Connector (DLC) in the driver's foot well.
- Turn on the ignition.
- Perform the guided function, "Check Electric Fuel Pumps".
• The fuel pump now runs for 60 seconds.
- Read the voltage value on the multi-meter.
• Specified value: approximately battery voltage
- Turn off the ignition.
If there is no voltage:
- Check the fuel pump relay activation and the wires for a open circuit or short circuit. Refer to the vehicle diagnostic tester.
If the voltage supply OK:
- Remove the fuel delivery unit. Refer to => [ Fuel Delivery Unit ] Fuel Delivery Unit.
- Check if the electrical wiring between the flange and the fuel pump is connected and has continuity.
If no open circuits are found:
- The fuel pump is faulty, replace the fuel delivery unit. Refer to => [ Fuel Delivery Unit ] Fuel Delivery Unit.
Current Draw, Checking
Test Conditions
• The battery voltage must be at least 12 volts.
• The fuses must be OK.
• All electrical consumers such as, for example, lights and rear window defogger, must be turned off.
• Fuel temperature inside the fuel tank above 10 °C (50 °F).
• The battery voltage and the temperature of the diesel fuel strongly influence the current draw of the fuel pump. Make sure the battery voltage is at least 12 volts and the temperature of the diesel fuel inside the fuel tank is not at the freezing point.
Test Sequence
- Remove the rear seat bench.
- Remove the cover - 1 - for the fuel delivery unit. The arrow - 2 - points in direction of travel.
- Disconnect the connector - 1 - from the fuel delivery unit flange.
- Connect the test instrument adapter/DSO (5-pin) (VAS 5565) between the connectors on the flange and cover.
- Connect the current clamp - A - to the red wire on test instrument adapter/DSO (5-pin) (VAS 5565) with the word "current clamp" on it.
• The current clamp from the multi-meter (V.A.G 1715) can also be connected to the red wire on test instrument adapter/DSO (5-pin) (VAS 5565) with the word "current clamp" on it.
- Connect the multi-meter (V.A.G 1526 D) to the current pickup (V.A.G 1526 B/2).
- Disconnect the connector - 1 - from the auxiliary fuel pump (inside the engine compartment on the right side).
- Connect the vehicle diagnostic tester - 1 - as follows:
- Connect the diagnostic cable - 2 - to the Data Link Connector (DLC) in the driver's foot well.
- Turn on the ignition.
- Perform the guided function "Check Electric Fuel Pumps".
• The fuel pump now runs for 60 seconds.
- Read the current draw on the multi-meter (V.A.G 1715).
Specified Value
• Minimum 5.5 amps
• Maximum 7.5 amps.
- Turn off the ignition.
If the current draw is below the specified value:
- The fuel pump is faulty, replace the fuel delivery unit. Refer to => [ Fuel Delivery Unit ] Fuel Delivery Unit.