Incorrect Fueling

Incorrect Fueling

Fueling incorrectly can cause insufficient lubrication which can lead to irreversible damage to the high pressure components, especially the high pressure pump. Damage in the form of seizing and particle abrasion can be expected. These particles will cause further damage in the pressure control valve and the injectors.

• This information guides the reader through the individual procedures like a flowchart.

Was the engine started with the incorrect fuel?

Yes, go to => [ Step 1 (Engine Was Started with Incorrect Fuel) ].

No, go to => [ Step 2 (Engine Was Not Started with Incorrect Fuel) ].

Step 1 (Engine Was Started with Incorrect Fuel)

- Drain the fuel tank as much as possible through the filler neck using the fuel extracting device (VAS 5190). Refer to => [ Fuel Tank with Reducing Agent Metering System, Draining ] Procedures.

- Remove the right single seat in the second row of seats.

- Fold the right carpet cutout to the side.

- Remove the flange cover nuts - 1 through 4 - and flange cover.

If the battery is connected, make sure that the fuel pump is not activated when the driver's door is opened. Fuel may leak out when the system is open.

- Disconnect the fuel return line, which is blue or has a blue mark, - 1 - from the fuel delivery unit. Disconnecting the couplings.

Vehicles with Vertical Fuel Filter

- Disconnect the fuel return line - 1 - and the fuel supply line - 2 - from the right locking flange by pressing the release buttons.

- Disconnect the connector - 3 - on the right locking flange.

Vehicles with Horizontal Fuel Filter

- Disconnect the fuel return line - 1 - and the fuel supply line - 2 - from the right locking flange by pressing the release buttons.

- Disconnect the connectors - 3 and 4 - on the right locking flange.

- Connect the hose (VAS 6551/5-2) from the pressure gauge to the fuel return line - arrow -.

- Place the other end of the hose (VAS 6551/5-2) into a container.

- Connect the vehicle diagnostic tester and perform the guided function "Activate Fuel Pump".

• The fuel pump is now activated.

- Repeat this procedure as necessary until the fuel tank is completely empty.

- Remove the fuel delivery unit. Refer to => [ Fuel Delivery Unit and Transfer Fuel Pump ] Fuel Delivery Unit and Transfer Fuel Pump.

- Check the fuel tank for any particles.

- Empty the fuel delivery unit reservoir.

- Check the reservoir visually for large contaminants and particles and on the screen.

Are there any particles?

Yes, go to => [ Step 3 (Particles in the Fuel Delivery Unit and Reservoir) ].

No, go to => [ Step 4 (No Particles in the Fuel Delivery Unit and Reservoir) ].

Step 2 (Engine Was Not Started with Incorrect Fuel)

- Drain the fuel tank as much as possible through the filler neck using the fuel extracting device (VAS 5190). Refer to => [ Fuel Tank with Reducing Agent Metering System, Draining ] Procedures.

- Remove the right single seat in the second row of seats.

- Fold the right carpet cutout to the side.

Vehicles with Horizontal Fuel Filter

- Connect the fuel return line - 1 -.

- Replace the fuel filter.

- Fuel the vehicle and perform a road test.

End

Step 3 (Particles in the Fuel Delivery Unit and Reservoir)

- Clean the fuel delivery unit and fuel tank using the suction pump (VAS 5226).

- Install the fuel delivery unit. Refer to => [ Fuel Delivery Unit and Transfer Fuel Pump ] Fuel Delivery Unit and Transfer Fuel Pump.

- Fill the fuel tank with 5 liters of diesel fuel.

- Drain the fuel tank completely as described in step 2.

- Replace the following high pressure components:

• High pressure pump.

• High pressure lines.

• Fuel rail, including the fuel pressure regulator valve and the fuel pressure sensor.

• Fuel injector.

• Fuel return lines (overflow lines).

• Fuel filter.

- Fuel the vehicle.

- Bleed the fuel system.

- Perform a road test.

End

Step 4 (No Particles in the Fuel Delivery Unit and Reservoir)

- Fill the fuel tank with 5 liters of diesel fuel.

- Drain the fuel tank completely as described in step 2.

- Replace the high pressure pump.

Only perform the steps below if the high pressure pump is faulty and has to be removed.

- Remove the bolts - arrows - and the metering unit - A - from the OLD high pressure pump.

- Check the metering unit and high pressure pump for particles.

Are there any particles?

Yes, go to => [ Step 5 (Particles in the High Pressure Pump) ].

No, go to => [ Step 6 (No Particles in the High Pressure Pump) ].

Step 5 (Particles in the High Pressure Pump)

- Replace the following high pressure components:

• High pressure line.

• Fuel rail, including the fuel pressure regulator valve and the fuel pressure sensor.

• Fuel injectors.

• Fuel return lines (overflow lines).

• Fuel filter.

- Fuel the vehicle.

- Bleed the fuel system.

- Perform a road test.

End

Step 6 (No Particles in the High Pressure Pump)

- Replace the fuel filter.

- Bleed the fuel system.

- Fuel the vehicle and perform a road test.

End