Fuel Rail and Injectors Overview
Fuel Rail and Injectors Overview
Special tools, testers and auxiliary items required
• Hose Clip Pliers (VAS 6362)
• Hoses are secured with spring-type clips.
• Hose clip pliers (VAS 6362) or (VAS 6340) are recommended for installing spring clamps.
• Follow the safety precautions when working on the diesel direct injection system. Refer to => [ Safety Precautions ] Diesel Fuel Injection.
• Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Diesel Fuel Injection.
Always follow these instructions 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:
• The fuel system parts/components between the fuel tank and the fuel high pressure pump being removed or replaced.
• It is necessary to perform the basic setting "checking transfer fuel pump" in order to bleed the fuel system.
• A fuel pump, fuel line (between the fuel tank and the fuel high pressure pump or the fuel filter was removed or replaced.
• It is necessary to perform the basic setting "checking transfer fuel pump" 1 time before starting the engine for the first time.
• If the high pressure fuel pump was removed or replaced, perform the basic setting "transfer fuel pump, checking" 3 times before starting the engine for the first time.
• Fill the fuel tank after installing the high pressure pump. Refer to => [ Fuel System, Filling and Bleeding ] Fuel System, Filling and Bleeding.
1 Protective Strip
• For the fuel rail - item 7 - and high pressure lines - item 5 -.
2 Fuel Return Lines
• With the pressure retention valve - item 8 - in => [ System Overview ] System Overview.
• The fuel return line must be routed correctly. They may be replaced only with the pressure retaining 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.
• Pressure retention valve in fuel return line, checking. Refer to => [ Pressure Retention Valve in Fuel Return Line, Checking ] Testing and Inspection.
3 Bolt/Nut
• 8 Nm
4 Fuel Return Line
• Blue or with a blue mark.
• Ensure the line is seated securely.
• From the fuel filter.
5 High Pressure Lines
• 28 Nm
• Between the fuel rail - item 7 - and fuel injector - item 20 -
The high pressure lines can be reused only after the following checks:
• Check the sealing cone on each high pressure line for deformation and cracks.
• The bores for the lines must not be deformed, narrowed or damaged.
• Do not use corroded lines again.
• Do not interchange
• When installing, the fuel injectors - item 20 - and high pressure lines may only be installed on the same cylinder as before.
• Do not change the angles of the high pressure lines
• Install without tension
6 Fuel Pressure Regulator Valve (N276)
• 80 Nm
• Removing and installing, refer to => [ ] Service and Repair.
7 Fuel Rail
8 Fuel Temperature Sensor (G81)
9 Fuel Supply Line
• Ensure the line is seated securely.
• Between the fuel temperature sensor - item 8 - and high pressure fuel pump - item 10 -
10 High Pressure Fuel Pump
• With the fuel metering valve (N290) - item 1 - in => [ System Overview ] System Overview.
• Removing and installing, refer to => [ High Pressure Fuel Pump ] High Pressure Fuel Pump.
• The fuel system "must" always be filled after replacing (never run dry) => [ Fuel System, Filling and Bleeding ] Fuel System, Filling and Bleeding.
11 Bolt
• 20 Nm
12 Bracket
• For the fuel temperature sensor - item 8 -.
13 Fuel Supply Line
• White or with white marks
• Ensure the line is seated securely.
• From the auxiliary fuel pump (V393).
• Auxiliary fuel pump, removing and installing. Refer to => [ (In-Line Electric Fuel Pump) ] Auxiliary Fuel Pump (V393) (In-Line Electric Fuel Pump).
14 Fuel Pressure Sensor (G247)
• 100 Nm
• Removing and installing, refer to => [ ] Service and Repair.
15 Bolt
• 22 Nm
16 Tensioning Plate
• Always replace
• Note the installed position, refer to => [ Tensioning Plate Installed Position ].
17 Nut
• 10 Nm
18 Sealing Cap
19 Bolt
• 5 Nm
20 Fuel Injector
• The following components and seals and/or O-ring must be replaced at every removal and installation: "tensioning bracket", "copper washer", "fuel injector unit shaft O-ring" and "fuel injector return O-ring".
• The following components and seals and/or O-ring must be replaced when replacing the fuel injector: "tensioning bracket", "fuel injector line", "copper washer" "fuel injector shaft O-ring" "fuel injector unit return O-ring"
• When installing, the fuel injectors and high pressure lines - item 5 - may only be installed on the same cylinder as before.
• Removing and installing, refer to => [ Fuel Injector ] Fuel Injector.
21 High Pressure Line
• 28 Nm
• Between the high pressure fuel pump - item 10 - and fuel rail - item 7 -.
The high pressure lines can be reused only after the following checks:
• Check the sealing cone on each high pressure line for deformation and cracks.
• The bores for the lines must not be deformed, narrowed or damaged.
• Do not use corroded lines again.
• Do not change the angles of the high pressure line.
• Install without tension
Tensioning Plate Installed Position
Fuel Return Line Differences
- A -, no ribbing: for connecting the overflow oil line, use a clamp.
- B -, with ribbing: for connecting the overflow oil line, do NOT use a clamp