Before Opening High Pressure Fuel Injection System

Before Opening High Pressure Fuel Injection System

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

Before opening high pressure parts, e.g. removing high pressure pump, fuel rail, fuel injectors, fuel pipes, etc., fuel pressure in high pressure area must be reduced to a residual pressure of approximately 6 bar. The procedure for this is as follows.

High fuel pressure, reducing

- Disconnect electrical connector from Fuel Metering Valve (N290) - 1 - and from Fuel Metering Valve 2 (N402) - 2 -.





- Allow engine to idle approximately 10 seconds.

• By disconnecting electrical connector from Fuel Metering Valve (N290) and from Fuel Metering Valve 2 (N402) at idle, fuel pressure is reduced to approximately 6 bar.

• Falling pressure can be observed if a vehicle tester is connected and engine control module (ECM) selected. And select display group 140 under "Read measured value block" function.

• Fuel pressure (actual value) is shown in display field 3.

- Switch off ignition.

CAUTION!
The fuel lines will continue to be filled with fuel, but will no longer be under high pressure. To open fuel system, wear protective eyewear and clothing to prevent injuries and contact with skin.

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

- After reducing high pressure, high pressure system must be opened immediately. To do this, place a clean cloth around connection to reduce residual pressure in system to approximately 6 bar. Escaping fuel must be absorbed.

- After completing work, generate readiness codes in control module in "Guided Functions" operating mode.