Fuel Metering Valve
The fuel metering valve is located on the high pressure pump. It regulates the amount of fuel to the high pressure pump cylinder.
The pressure in the fuel rail depends on the amount of fuel supplied to the high pressure pump cylinders. The Engine Control Module (ECM) calculates the desired pressure and regulates the valve via a PWM signal.
The pressure in the fuel rail varies from approximately 11 MPa at idle speed to approximately 20 MPa at full load and engine speed in excess of 2250 RPM.
If the fuel pressure in the fuel rail was to exceed approx 23 MPa (230 bar) a safety valve in the high pressure pump opens and the fuel is led away but remains in the high pressure system and is used for the next pressure cycle.
The fuel metering valve is diagnosed by the Engine Control Module (ECM). The control current to the valve can be read off.