Circuit description: Notes

The high pressure fuel system of the direct injection system consists of electromagnetic spill valves that adjust injection amount of high-pressure fuel, camshaft-driven plungers that pressurize fuel, and check valve that mechanically opens and closes path leading to the fuel delivery pipes. Fuel pump ASSY (high-pressure side) is installed to the cylinder head cover, and it is driven by the cam of the intake camshaft in the engine left bank. The pump plunger, driven by the rotating camshaft, moves up and down to pressurize fuel. The pressurized fuel pushes and opens the check valve, and is pumped into the fuel delivery pipes. The engine control computer manages electromagnetic spill valve to adjust the fuel pressure. In order to maintain the target fuel pressure, the engine control computer monitors the pressure with the signal from the fuel pressure sensor. When the fuel pressure of the fuel delivery pipe abnormally rises, the relief valve integrated into the fuel pump ASSY (high-pressure side) opens and allows the fuel to return to the fuel tank.