Fuel System Schematic Overview

Fuel System Schematic Overview

• Follow the guidelines for a clean working environment when working on the fuel system. Refer to => [ Clean Working Conditions and Fuel System Work Instructions ] Clean Working Conditions and Fuel System Work Instructions.

• Always follow these rules before and during work.

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

If fuel system components between the fuel tank and high pressure fuel pump are removed or replaced, perform a basic setting "Transfer Fuel Pump, Checking" to bleed the fuel system.

If the auxiliary fuel pump, the fuel line between the fuel tank and high pressure fuel pump or the fuel filter is removed or replaced, perform the basic setting "Initial Fueling" one time before starting the engine for the first time.

If the fuel high pressure pump was removed or replaced, perform a basic setting "channel 35" three times before starting the engine for the first time.

Fill the fuel tank after installing the high pressure pump. Refer to => [ Fuel System, Bleeding and First Time Filling ] Fuel System, Bleeding and First Time Filling.






1 Fuel Metering Valve (N290)

• Do not open.

2 High Pressure Fuel Pump

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

• High pressure pump overview. Refer to => [ High Pressure Pump Overview ] High Pressure Pump Overview.

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

3 Fuel Rail (High Pressure Reservoir)

• For cylinder bank 1.

4 Fuel Pressure Regulator Valve (N276)

• On cylinder bank 1.

• Cannot be reused again.

• Removing and installing, refer to => [ Fuel Pressure Regulator Valve N276 ] Service and Repair.

5 Fuel Pressure Sensor (G247)

• 30 Nm

• Installed in the fuel rail for cylinder bank 2.

• Removing and installing, refer to => [ Fuel Pressure Sensor G247 ] Service and Repair.

6 Fuel Rail (High Pressure Reservoir)

• For cylinder bank 2.

7 Fuel (Piezo) Injector

• Injectors 1 through 6.

• Removing and installing => [ Fuel (Piezo) Injectors ] Service and Repair.

8 Fuel Return Lines (Leak Lines)

• Do not disassemble the fuel return lines. Replace them completely with the pressure retention valve.

• Run the engine at idle for approximately two minutes after replacing to bleed the fuel system and then check the fuel return lines for leaks.

9 Pressure Retention Valve

• The pressure retention valve always maintains a residual pressure (control quantity) of approximately 10 bar (145 psi) in the fuel return lines.

• The injectors need this control quantity to function correctly.

• The valve can be replaced only with the fuel return line.

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

• Checking, refer to => [ Fuel Return Line Pressure Retention Valve, Checking ] Testing and Inspection.

10 Fuel Tank

• With the transfer fuel pump.

11 Fuel Filter

• Fuel filter overview.

12 Auxiliary Fuel Pump (V393)