Incorrect Fuel

Incorrect Fuel

CAUTION!
Incorrect fuel 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.

Two incorrect fuel scenarios are possible:

• 1. Situation: incorrect fuel was noticed BEFORE starting the engine and the engine was NOT started. Refer to => [ Procedure for Scenario 1 ].

• 2. Situation: incorrect fuel was noticed AFTER starting the engine. Contaminated or incorrect fuel has entered the fuel system and reached the high pressure components. Refer to => [ Procedure for Scenario 2 ].

Procedure for Scenario 1

- DO NOT turn on the ignition.

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

- Disconnect the connector from the auxiliary fuel pump (V393) (inline electric fuel pump) in the engine compartment. Refer to => [ Auxiliary Fuel Pump Overview ] Auxiliary Fuel Pump Overview.

- Remove the rear bench seat.

- Remove the cover from the fuel delivery unit.

• Press in the securing ring to disengage the fuel line.

- Remove the fuel supply line, which is black or has a black mark, - 2 - from the fuel delivery unit.





- Connect the (VAS 6550/1) to the fuel supply - 2 - on the flange.

- Place the open end of the (VAS 6550/1) in a suitable container.

- Connect the vehicle diagnostic tester and perform the "Empty fuel system" Guided Function.

• The fuel pump is activated.

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

- Fill the fuel tank with 5 liters of diesel fuel and empty it again using the "Empty fuel system" Guided Function.

- Connect the fuel supply line, which is black or has a black mark, - 2 - to the fuel delivery unit.





- Connect the connector to the auxiliary fuel pump (inline electric fuel pump) in the engine compartment. Refer to => [ Auxiliary Fuel Pump Overview ] Auxiliary Fuel Pump Overview.

- Fill the fuel tank completely with diesel fuel.

- Perform a test drive.

Procedure for Scenario 2

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

- Remove the rear bench seat.

- Remove the cover from the fuel delivery unit.

• Press in the securing ring to disengage the fuel line.

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





- Connect the (VAS 6550/1) from the pressure gauge to the fuel return line - 1 -.

- Place the open end of the (VAS 6550/1) in a suitable container.

- Connect the vehicle diagnostic tester and perform the "Empty fuel system" Guided Function.

• The fuel pump is activated.

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

- Remove the fuel delivery unit and check the fuel tank for contamination and shavings. Refer to => [ Fuel Delivery Unit, Fuel Level Sensor and Suction Jet Pumps ] Fuel Delivery Unit, Fuel Level Sensor and Suction Jet Pumps.

- Clean the fuel tank if necessary and connect the fuel delivery unit.

- Fill the fuel tank with 5 liters of diesel fuel and empty it again using the "Empty fuel system" Guided Function.

- Replace the fuel filter. Refer to => [ Fuel Filter and Cooler Overview ] Description and Operation.

- Replace the following high pressure components:

• High pressure pump. Refer to => [ Diesel Direct Fuel Injection System ] Diesel Direct Fuel Injection System.

• High pressure lines. Refer to => [ Diesel Direct Fuel Injection System ] Diesel Direct Fuel Injection System.

• Fuel rail including the fuel pressure regulator valve (N276) and fuel pressure sensor (G247). Refer to => [ Diesel Direct Fuel Injection System ] Diesel Direct Fuel Injection System.

• Fuel injectors. Refer to => [ Fuel Injectors ] Service and Repair.

• Fuel return lines (overflow lines). Refer to => [ Diesel Direct Fuel Injection System ] Diesel Direct Fuel Injection System.

- Connect the fuel return line, which is blue or has a blue mark - 1 -.





- Fill the fuel tank completely with diesel fuel.

- Fill/bleed the fuel system with the "Bleed fuel system" Guided Function.

- Perform a test drive.