High Pressure Fuel Pump
The high pressure fuel pump (9) is a mechanical one cylinder design driven by an eccentric on the exhaust camshaft (1) of bank 2. High pressure fuel is regulated by the fuel rail pressure (FRP) regulator, which is a part of the high pressure fuel pump. The FRP regulator is a magnetic actuator which controls the inlet valve of the high pressure pump. The ECM provides battery voltage on the actuator high circuit and ground on the actuator low reference circuit. Both circuits are controlled by the ECM. When the ECM deactivates the FRP regulator, both circuits are disabled and the inlet valve is held open with spring pressure. When the ECM activates the FRP regulator, the low circuit driver connects the low reference circuit to ground and the high circuit driver pulse-width modulates (PWM) the high circuit. The ECM uses the camshaft and crankshaft position sensor inputs to synchronize the FRP regulator with the position of the eccentric on the camshaft. The ECM regulates fuel pressure by adjusting the portion of each pump stroke that provides fuel to the rail. The high pressure fuel pump also contains an integrated pressure relief valve.