Fuel Pressure Regulator
The fuel pressure regulator is located downstream of the fuel injector on the fuel rail. Its function is to maintain a constant 14.5 psi (1.0 kg/cm2 ) across the fuel injector tip. The regulator uses a spring loaded rubber diaphragm to uncover a fuel return port. When the fuel pump becomes operational, fuel flows past the injector into the regulator, and is restricted from flowing any further by the blocked return port. When fuel pressure reaches 14.5 psi (1.0 kg/cm2 ) it pushes in the diaphragm, compressing the spring, and uncovers the fuel return port. The diaphragm and spring will constantly move from an open to closed position to keep the fuel pressure constant.