Fuel Pressure Regulator: Description and Operation

Fuel Pressure Regulator Assembly:

PURPOSE
The fuel pressure regulator maintains a constant fuel pressure in the fuel rail based on engine load and also routes any excess fuel back to the fuel tank.

OPERATION
The pressure regulator is a diaphragm-operated relief valve with fuel pump pressure on one side, and regulator 'spring pressure and intake manifold vacuum on the other. Its function is to maintain a constant pressure differential across the injectors at all times. The pressure regulator compensates for engine load by increasing fuel pressure as engine vacuum drops.

With the ignition "ON" and engine "OFF" (zero vacuum), fuel pressure at the pressure test connection should be 284 - 325 kPa (41 - 47 psi). If the pressure is too low, poor performance could result. If the pressure is too high, excessive odor and a Code 45 may result.