Diagnose fuel pump failure Audi A6

Diagnosing a Fuel Pump Failure in an Audi A6 C7 (2011-2018)

Step 1: Preliminary Checks

• Tools Required: OBD-II Scanner, Multimeter, Fuel Pressure Gauge.
• Procedure:
  1. Check for Diagnostic Trouble Codes (DTCs):
     • Connect the OBD-II scanner to the vehicle's diagnostic port.
     • Retrieve and note any diagnostic trouble codes. Codes related to fuel delivery include P0087 (Fuel Rail/System Pressure - Too Low) or P0230 (Fuel Pump Primary Circuit).

Step 2: Listen for Fuel Pump Operation

• Procedure:
  1. Turn the ignition key to the "ON" position without starting the engine.
  2. Listen for a humming sound from the fuel tank area, indicating the fuel pump is priming. If there is no sound, the pump may not be receiving power or may have failed.

Step 3: Check Fuel Pressure

• Tools Required: Fuel Pressure Gauge.
• Procedure:
  1. Locate the fuel rail on the engine and find the Schrader valve (pressure testing port).
  2. Attach the fuel pressure gauge to the Schrader valve.
  3. Turn the ignition to the "ON" position and check the fuel pressure reading.
  4. Compare the reading to the manufacturer’s specification (typically around 50-60 PSI for the Audi A6 C7).
  5. If pressure is below specification, this indicates a potential issue with the fuel pump or fuel delivery system.

Step 4: Electrical Testing

• Tools Required: Multimeter.
• Procedure:
  1. Access the fuel pump electrical connector by removing the rear seat or accessing through the trunk.
  2. Disconnect the electrical connector from the fuel pump.
  3. Use a multimeter to check for voltage at the connector while the ignition is in the "ON" position.
  4. Verify that there is proper voltage (typically 12 volts) reaching the fuel pump.
  5. If voltage is present and the pump does not operate, the pump is likely faulty.

Repair Instructions

Step 1: Replacement of the Fuel Pump

• Tools Required: Socket set, Screwdrivers, Fuel Line Disconnect Tool.
• Procedure:
  1. Safety First: Disconnect the negative battery terminal to prevent accidental short circuits.
  2. Access the Fuel Pump:
     • Remove the back seat or access panel in the trunk to reach the fuel pump assembly.
  3. Depressurize the Fuel System:
     • Carefully remove the fuel pump relay and start the engine to relieve pressure.
     • Once the engine stalls, the system is depressurized.
  4. Remove Fuel Pump Assembly:
     • Disconnect the electrical connector and fuel lines from the pump.
     • Use a screwdriver or appropriate tool to loosen and remove the retaining ring.
     • Carefully lift the fuel pump assembly from the tank.
  5. Install New Fuel Pump:
     • Position the new fuel pump assembly into the fuel tank.
     • Secure it with the retaining ring.
     • Reconnect the fuel lines and electrical connector.
  6. Reassemble and Test:
     • Reinstall any panels or seats removed.
     • Reconnect the battery.
     • Turn the ignition to "ON" to prime the fuel system and check for leaks.
     • Start the engine and verify proper operation.

Conclusion

If these steps confirm a fuel pump failure, replacing the fuel pump should restore normal operation. If issues persist after replacement, further diagnosis of the fuel delivery system or engine management system may be necessary.