Fuel Pressure Regulator: Description and Operation

Fuel Pressure Regulator:

Fuel pump output pressure is 138 psi (950 kPa). The fuel pressure regulator is used to maintain a constant pressure differential at the fuel injector tip of 43 psi psi (300 kPa). The pressure regulator uses a vacuum assisted spring loaded diaphragm to control the fuel return port in order to maintain constant pressure. When fuel pressure acting on the regulator diaphragm exceeds 43 psi (300 kPa), the regulator spring is compressed and the fuel return port is opened. When fuel pressure drops below 43 psi (300 kPa), spring tension causes the diaphragm to block the fuel return port. As manifold vacuum increases during deceleration, less pressure is needed to supply the same amount of fuel into the air flow. In order to fine tune the fuel pressure under all operating conditions manifold vacuum assists in opening the fuel port during high vacuum conditions. If no vacuum is applied fuel pressure will be slightly higher.