Fuel Pressure Regulator: Description and Operation

Fuel Pressure Regulator And Vacuum Control Hose:

The fuel pressure regulator is mounted on the fuel rail. The primary function of the regulator is to maintain a constant pressure difference between the fuel pressure at the injector nozzles and the absolute air pressure (manifold vacuum) in the intake manifold. This is because the ECU meters fuel by modifying only the "ON" time of the injector. The ECU, during its fuel metering calculations, relies on the pressure differential remaining constant. To accomplish this goal the regulator has a vacuum line to sense intake manifold pressure. With this input the regulator can control the fuel pressure, in direct response to intake manifold pressure (vacuum) fluctuations.