Fuel Tank: Service Precautions

Before Opening High Pressure Fuel Injection System

The fuel injection system is separated into a high-pressure section (max. approximately 140 bar) and a low-pressure section (approximately 7 bar).

Before opening high pressure parts, for example removing high pressure pump, fuel rail, fuel injectors, fuel pipes or fuel pressure sensor (G247), fuel pressure in high pressure area must be reduced to a residual pressure of approximately 7 bar. The procedure for this is as follows.

High Fuel Pressure, Reducing

- Connect the vehicle diagnosis tester.

- Start engine and run at idle speed.

- Select engine electronics in OBD.

- Then select basic setting.

- Select pressure reduction inside the rail from the list.

- Then select measured values.

- Select operating instructions and fuel pressure from the list.

- To activate the basic setting, perform the operating instruction.

- Check the fuel pressure on the tester.

• The fuel pressure reduces to a specified value.

- Turn off the engine with the pedal operated.

Do not let fuel come into contact with skin.

• Wear protective eye wear and clothing when opening the fuel system.

• Lay clean cloths around the connection before opening the high pressure area to collect any fuel that leaks out.

- After reducing fuel pressure, place a clean cloth around the connection and open the high pressure system immediately. Escaping fuel must be absorbed.

• If the high pressure system is not opened immediately, the pressure will increase because of post-heating.

Final Procedures

- Erase the DTC memory and generate the readiness code in the engine control module in guided functions.