Fuel Rail Overview

Fuel Rail Overview


The fuel system is under pressure!

• Before opening high pressure components of the fuel injection system, the fuel pressure must be relieved to residual pressure, refer to => [ High Side Fuel Pressure, Releasing ] Service and Repair.






1 Fuel Injector

• Cylinder 1 fuel injector (N30).

• Cylinder 2 fuel injector (N31).

• Cylinder 3 fuel injector (N32).

• Cylinder 4 fuel injector (N33).

• With a combustion chamber seal (Teflon seal), always replace; refer to => [ Fuel Injector Teflon Seal ] Fuel Injector Teflon Seal.

• Replace the O-rings

• Note the correct installed position.

• Removing and installing, refer to => [ Fuel Injector ] Fuel Injector.

• Cleaning, refer to => [ Fuel Injector, Cleaning ] Service Precautions.

2 Support Ring

3 Fuel Rail

• Removing and installing, refer to => [ Fuel Rail, Separating from the Intake Manifold ] Intake Manifold with Fuel Rail.

• Fuel rail, separating from the intake manifold. Refer to => [ Fuel Rail, Separating from the Intake Manifold ] Intake Manifold with Fuel Rail.

4 High Pressure Pump

• An electrical fuel pump, located in the fuel tank, supplies fuel to the mechanical high pressure pump at a pressure of approximately 7 bar.

• When installing the high pressure pump, make sure that no dirt enters the fuel system.

• The fuel system must be pressureless to install the high pressure pump, releasing the fuel pressure, refer to => [ High Side Fuel Pressure, Releasing ] Service and Repair.

• Install the fuel line to the fuel rail free of tension.

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

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

5 Cam Follower

• Remains inserted in the cylinder head after removing the high pressure pump, removable.

6 Fuel Pressure Regulator Valve (N276)

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

7 Bolts

• M6 threads: 8 Nm + 90° (1/4) additional turn. Replace.

• M8 threads: 20 Nm

8 Connecting Piece

• 22 Nm

• Always replace.

• For the high pressure fuel line.

- Check the tightening specification before installing the high pressure fuel line.

9 High Pressure Fuel Line

- Tighten the high pressure fuel line union nut hand tight. Align so it is free of stress.

• Union nut: 18 Nm

10 Intake Manifold Flaps

11 Gasket

• Always replace.

12 Intake Manifold

• Removing and installing, refer to => [ Intake Manifold with Fuel Rail ] Intake Manifold with Fuel Rail.

13 Vacuum Actuator

• For the variable intake manifold.

• Checking, refer to => [ Variable Intake Manifold, Checking ] Testing and Inspection.

14 Throttle Valve Control Module (J338)

• With the EPC throttle drive (G186) , the EPC throttle drive angle sensor 1 (G187) and the EPC throttle drive angle sensor 2 (G188).

• After replacing the throttle valve control module, it must be readapted to the engine control module (J623). Refer to "Guided Functions" in the vehicle diagnostic tester.

• Removing and installing, refer to => [ Throttle Valve Control Module (J338) ] Removal and Replacement.

• Cleaning, refer to => [ Throttle Valve Control Module, Cleaning ] Procedures.

15 Bolts

• Tighten to 3 Nm, and then tighten to 9 Nm.

16 Intake Manifold Runner Position Sensor (G336)

• To remove and install, remove the intake manifold; refer to => [ Intake Manifold with Fuel Rail ] Intake Manifold with Fuel Rail.

17 Fuel Pressure Sensor (G247)

• 27 Nm

• Lubricate the threads with clean engine oil.

• Checking, refer to => [ Fuel Pressure Sensor, Checking ] Testing and Inspection.

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