Fuel Pressure Regulator: Description and Operation

Pressure Regulator:

The fuel pressure regulator is a diaphragm-operated relief valve consisting of a diaphragm, spring and valve. It keeps the fuel pressure to the injector at approximately 180 kPa (26 psi) higher than that in the intake manifold at all times.

The pressure applied to the chamber "A" of the fuel pressure regulator is intake manifold pressure and that to chamber "B" is fuel pressure. When the fuel pressure rises more than 180 kPa (26 psi) higher than the intake manifold pressure, the fuel pushes the valve in the regulator open and excess fuel returns to the fuel tank via the return pipe.