Fuel Delivery, 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
Fuel Delivery, Checking
- Remove the rear seat bench.
- Remove the cover - 1 - with fuel pump control module (J538) - 2 - from the fuel delivery unit.
- First, pull on the connector - arrow - without pressing the retainer to make sure it is connected securely. If the connector was not connected correctly, it could cause a fault.
- Disconnect the connector.
- Check the contacts on the connector and the fuel delivery unit for damage.
- Install the (VAS 5565) between the connectors on the fuel delivery unit and cover.
- Connect the (V.A.G 1348/3A) to the (VAS 5565) and the battery positive clamp in the engine compartment.
• This step allows the fuel pump to run when the engine is not running.
The fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before disconnecting the connection, wrap a cloth around the connection. Then, disconnect the connection carefully to release the pressure.
- Disconnect the supply line (metal coupling) - arrow - and collect leaking fuel in a cloth.
• Press in the securing ring to disengage the fuel lines.
- Connect the (VAS 6550) to the fuel supply line using (VAS 6550/2). Hold the other end of the (VAS 6550/1) in the measuring container.
- Make sure the drain is closed and the shut-off valves are open.
Danger of spraying. Wear protective goggles and protective clothing to prevent injuries and contact with skin. Hold the container in front of free the connection of pressure measuring device.
- Operate the (V.A.G 1348/3A). Slowly close the shut-off valve - arrow - until the (VAS 6550) shows 4 bar. From this point on do not move position of shut-off valve.
- Empty the measuring container.
- The fuel delivery rate of the fuel pump is dependent on battery voltage. Connect the (V.A.G 1715) to connectors - 1 and 5 - of (VAS 5565).
- Operate the (V.A.G 1348/3A) for 60 seconds and simultaneously the measure voltage at the fuel pump.
- Compare the quantity of fuel delivered with the specification.
*) Minimum delivery rate cm³/60 s
**) Voltage at fuel pump with engine running in idle and the pump is on.
Example:
During the test, a voltage of 10.5 volts is measured. This results in a minimum delivery quantity of approximately 1,200 cm³/60 s.
If the Specification is not Obtained:
- Check the fuel lines for possible restrictions (kinks) or blockages.
If no Malfunction can be Found:
- Remove the cap from the fuel filler neck and repeat the test. If the fuel delivery quantity is now reached, check the fuel tank ventilation.
If the Specification is again not Obtained:
- Check the fuel filter as follows:
The fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before disconnecting the connection, wrap a cloth around the connection. Then, disconnect the connection carefully to release the pressure.
- Disconnect the fuel supply line - arrow - from the fuel filter.
- Connect the (VAS 6550) to the fuel supply line using (VAS 6550/1). Hold the other end of the (VAS 6550/2) in the measuring container.
- Make sure the drain is closed and the shut-off valves are open.
- Operate the (V.A.G 1348/3A). Slowly close the shut-off valve - arrow - until the (VAS 6550) shows 4 bar. From this point on do not move position of shut-off valve.
- Empty the measuring container.
- Repeat the fuel delivery test.
If the Minimum Delivery Rate is now Obtained:
- Replace the fuel filter.
If the Minimum Delivery Rate is again not Obtained:
- Remove the fuel delivery unit and check fuel strainer for contamination.
Only when up to now no Malfunction has been Detected:
- Replace the fuel delivery unit.
Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply (for example, intermittent loss of fuel supply):
- Check the fuel pump current draw. Refer to => [ Current Draw, Checking ]. Current Draw, Checking