Fuel Pressure Regulator: Description and Operation

Fig. 12 Pressure regulator:

The pressure regulator consists of a sealed, spring loaded diaphragm, with a connection for intake manifold vacuum. Fuel is provided to the fuel injectors under approximately 2.5 bar (36 psi).
A connection for intake manifold vacuum provides a constant pressure differential which ensures that the amount of fuel injected is solely dependent upon injector 'open' time. Excess fuel is returned to the fuel tank.