Diesel Fuel System Overview

Fuel System Overview


• Follow the guidelines for a clean working environment when working on the fuel system, refer to => [ Fuel System ] Fuel System.

• Always follow these rules before and during work.


Follow the points below to avoid running the high pressure fuel pump dry (very low tolerances) and to start the engine quickly after replacing the components:

• If the fuel system components between the fuel tank and the high pressure fuel pump are removed or replaced, then a fuel first filling must be performed.

• It is necessary to bleed the fuel system before starting the engine for the first time if the fuel pump, the fuel line (between the fuel tank and the fuel high pressure pump) or the fuel filter were removed.

• If the fuel high pressure pump was removed or replaced, then bleed the fuel system before starting the engine for the first time.

Filling the fuel for the first time, refer to => [ Fuel System, Filling and Bleeding ] Fuel System, Filling and Bleeding.

• Not paying attention to the first filling will damaged the fuel high pressure pump.






1 - Fuel Tank

• With transfer fuel pump (G6)

2 - Fuel Filter

• Fuel filter assembly overview

• Fuel filter, replacing

3 - Auxiliary Fuel Pump (V393)

4 - Filter

5 - Fuel Temperature Sensor (G81)

6 - High Pressure Pump

• After replacing, the fuel tank "must" be filled (never run dry), refer to => [ Fuel System, Filling and Bleeding ] Fuel System, Filling and Bleeding

• Removing and installing, refer to => [ High Pressure Pump ] High Pressure Pump

7 - Fuel Metering Valve (N290)

• Do not open

8 - Fuel Pressure Regulator Valve (N276)

• 80 Nm

• Cannot be used again

• Removing and installing => [ Fuel Pressure Regulator Valve (N276) ] Service and Repair

9 - Fuel Rail

10 - Fuel Pressure Sensor (G247)

• 100 Nm

• Removing and installing => [ Fuel Pressure Sensor (G247) ] Fuel Pressure Sensor (G247)

11 - Pressure Retention Valve

• The check valve always maintains a residual pressure (control quantity) of approximately 10 bar in the fuel return lines.

• The fuel injectors require this control quantity to function correctly.

• The check valve can be replaced only with the complete fuel return lines.

• The engine must run at idle for approximately two minutes after replacing to bleed the fuel system.

• Check pressure retaining valve, refer to => [ Pressure Retention Valve in Fuel Return Line, Checking ] Pressure Retention Valve In Fuel Return Line, Checking

12 - Injector

• Cylinder 1 fuel injector (N30)

• Cylinder 2 fuel injector (N31)

• Cylinder 3 fuel injector (N32)

• Cylinder 4 fuel injector (N33)

• Removing and installing, refer to => [ Fuel Injectors ] Removal and Replacement