•  An integral transfer pump is found inside the supply pump, and this transfers the fuel from the tank to the supply pump.

•  The high pressure pump supplies fuel through the high pressure system into the common rail and to the injectors and builds up the injection pressure there.

•  Injection timing and quantity are calculated by the PCM.

•  Using various input variables, the PCM controls the piezoelectrically operated injectors, which inject the required quantity of fuel into the applicable combustion chamber.

•  The fuel pressure sensor on the common rail provides the PCM with information on the current fuel pressure. Another variable is the fuel temperature.

•  Based on these input variables, the PCM controls the fuel metering for the system by using the fuel metering valve and the fuel pressure regulator, so that the optimum fuel pressure is available for every operating state.

•  Excess fuel passes through the fuel return collector pipe, past the fuel temperature sensor, and back to the fuel tank.

•  In the tank a venturi pump ensures that the fuel returned helps the filling of the fuel supply unit in the tank.