Sunfire L4-2.2L VIN 4 (1996)
Fuel Pressure Regulator: Description and Operation
The fuel pressure regulator assembly is a diaphragm-operated relief valve with fuel pump pressure on one side, and a regulator spring pressure and intake
manifold vacuum on the other side. The regulator's function is to maintain a constant pressure differential across the injectors at all times. The pressure
regulator compensates for engine load by increasing the fuel pressure as the engine vacuum drops. The fuel pressure regulator is serviced as a complete
assembly. With the ignition ON and engine OFF (zero vacuum), fuel pressure should be 284-325 kPa (41-47 psi). Whenever the pressure is too low,
poor performance and a DTC P0171 could result. Whenever the pressure is too high, excessive odor and a DTC PO172 could result.
