Fuel Pressure Regulator
The non-adjustable pressure regulator controls fuel pressure, maintaining a constant 35 psi (2.55 kg/cm2 ) difference between fuel pressure and intake manifold vacuum. Fuel exerts pressure against spring-loaded diaphragm, which deflects uncovering return line to fuel tank. Engine vacuum also works with fuel pressure against diaphragm when high vacuum is present. Diaphragm then deflects at about 28 psi (2.0 kg/cm2 ) instead of 35 psi (2.55 kg/cm2 ).