Beretta L4-138 2.3L DOHC QUAD 4 (1991)
Fuel Pressure Regulator: Description and Operation
Fuel Pressure Regulator Assembly
The fuel pressure regulator assembly is a diaphragm-operated relief valve with fuel pump pressure on one side, and regulator spring pressure and intake
manifold vacuum on the other.
The function of the regulator 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. The pressure regulator is mounted at the end of the fuel rail, and is serviced as a
complete assembly.
The system operates in an acceptable pressure range of 224-325 kPa (32.0-47.0 psi) with the engine running. If the pressure is too low, poor
performance and a Code 44 could result. If the pressure is too high, excessive odor and a Code 45 could result. CHART A-7 has information on
diagnosing fuel pressure conditions.
