Primary Fuel Pressure Regulator

The primary fuel pressure regulator is contained in the left fuel sender assembly. 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. A software bias compensates the injector on-time because the fuel pressure regulator is not referenced to the manifold vacuum. The primary fuel pressure regulator keeps fuel available to the injectors at a regulated pressure.