Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated relief valve with injector pressure on one side and manifold pressure on the other. The function of the regulator is to maintain a constant pressure at the injectors at all times. Some models also use a fuel pressure accumulator to compensate for high fuel demand conditions. The pressure regulator also compensates for engine load by increasing fuel pressure when it sees low engine vacuum.
The pressure regulator is mounted on the fuel rail and is serviced separately. If pressure is too low, poor performance could result. If the pressure is too high, excessive odor and a code 45 may result. See Fig 1 .
NOTE:
The SFI turbo engine pulses only 1 injector at a time, thus the fuel pressure drop is small. Therefore, the SFI system does not use a fuel pressure accumulator.