Fuel Pressure Regulator: Description and Operation

Fig. 3 Fuel pressure regulator cross sectional view:

The fuel pressure regulator, Fig. 3, is attached to the fuel supply manifold assembly downstream from the fuel injectors. It regulates the fuel supplied to the injectors. The regulator is a diaphragm operated relief valve. One side of the diaphragm senses fuel pressure and the other side senses intake manifold pressure. Nominal fuel pressure is established by spring preload applied to the diaphragm. Balancing one side of the diaphragm with manifold pressure maintains a constant fuel pressure drop across the injectors.