Procedures

High Side Fuel Pressure Releasing

Special tools, testers and auxiliary items required

• Assembly tool (T10118)

Procedure

CAUTION!
The fuel injection system is divided into a high pressure side (maximum approximately 120 bar) and a low pressure side (approximately 6 bar):

• Before opening the high pressure side , for example, for removing the high pressure pump, fuel rail, fuel injectors, fuel pipes or fuel pressure sensor the fuel pressure in the high pressure side must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows.

- Disconnect the electrical connector - 1 - from the fuel pressure regulator valve using the (T10118).





- Allow the engine to idle approximately 10 seconds.

• When the fuel pressure regulator valve electrical connector is disconnected during idle, the pressure in the high pressure side decreases to approximately 6 bar.

• After the high pressure has been released, the high pressure side must be opened, otherwise the pressure increases again due to the warming of the fuel.

- Turn off the ignition.

CAUTION!
Fuel lines are pressurized!

• Wear protective goggles and protective clothing to prevent injuries and contact with skin.

• Before opening the high pressure side, place a cloth around the connection.

- Place a clean cloth around the connection and carefully open, to release the residual pressure of approximately 6 bar. Escaping fuel must be absorbed.

• By separating the connections, Diagnostic Trouble Codes (DTCs) are stored to memory. After assembling, check the fault memory and erase, if necessary.

- Check the engine control module (ECM) DTC memory and erase all DTC entries which may have occurred during assembly.

• If the DTC memory was erased, generate a readiness code.