The fuel system is demand-controlled on the high and low-pressure sides. On the low-pressure side, the engine control unit regulates the fuel pump control unit J538 and with it the delivery rate of the fuel pump in the fuel tank. On the high pressure side, the engine control unit regulates the fuel metering valve N290 directly at the high-pressure pump. To monitor the pressure levels in the system, two fuel pressure senders send their respective signals to the engine control unit. The central element of the fuel system is a demand-controlled single-piston high-pressure pump. This generation III fuel pump by Hitachi is driven by a three-lobe cam seated on the exhaust camshaft. The system with a maximum pressure of 120 bar. The pressure-limiting valve in the pump opens at a pressure of approx. 145 bar.
Caution: danger of injury. The system operates at very high pressures. To open the high-pressure side, always follow the instructions given in this section (later stage).