High Pressure Fuel Pump
The high pressure fuel pump is a mechanical one cylinder design driven by an additional three lobe cam on the camshaft. High pressure fuel is regulated by the high pressure fuel pump actuator, which is a part of the high pressure fuel pump. The high pressure fuel pump actuator is a magnetic actuator which controls the inlet valve of the high pressure fuel pump. The ECM provides battery voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. When deactivated, both drivers are disabled and the inlet valve is held open with spring pressure. When activated, the actuator low control circuit driver connects the low control circuit to ground and the actuator high control circuit driver pulse-width modulates (PWM) the high control circuit. The ECM uses the camshaft and crankshaft position sensor inputs to synchronize the actuator with the position of each of the three camshaft lobes. The ECM regulates fuel pressure by adjusting the portion of each pump stroke that provides fuel to the fuel rail. The high pressure fuel pump also contains an integrated pressure relief valve.