Fuel Pressure Regulator: Operation

The pressure regulator is a mechanical device that is calibrated to maintain fuel system operating pressure of approximately 379 kPa (55 psi) at the fuel injectors.

It contains a diaphragm, calibrated springs and a fuel return valve.

Fuel is supplied to the regulator by the electric fuel pump through an opening tube at the bottom of regulator.

The fuel pump module contains a check valve to maintain some fuel pressure when the engine is not operating. This will help to start the engine.

If fuel pressure at the pressure regulator exceeds approximately 56 psi, an internal diaphragm closes and excess fuel pressure is routed back into the tank through the pressure regulator. A separate fuel return line is not used with any gas powered engine.

The pressure regulator is a mechanical device that is NOT controlled by the PCM or engine vacuum.