Fuel Pressure Regulator

The fuel pressure regulator is contained in the fuel pump module. The fuel pressure regulator is a diaphragm relief valve. The diaphragm has fuel pressure on one side and regulator spring pressure on the other side. Fuel pressure is controlled by a pressure balance across the regulator. The fuel system pressure is constant and is no longer a function of engine load or manifold vacuum. A software bias compensates the injector on-time based on the signal from the manifold absolute pressure (MAP) sensor.