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.

NOTE: With the ignition "ON" and engine "OFF" (zero vacuum), fuel test port pressure 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.