F 350 2WD Super Duty V8-5.4L SOHC VIN L (2002)
Fuel Pressure Regulator: Description and Operation
Fuel Pressure Regulator
Fuel Pressure Regulator
The fuel pressure regulator (Figure 70) is attached to the fuel rail downstream of the fuel injectors. It regulates fuel pressure supplied to the fuel
injectors. The regulator is a diaphragm-operated relief valve. One side of the diaphragm senses fuel pressure and the other side is connected to the
intake manifold vacuum. Fuel pressure is established by a spring preload applied to the diaphragm. Balancing one side of the diaphragm with
manifold vacuum maintains a constant fuel pressure drop across the fuel injectors. Fuel pressure is high when engine vacuum is low. Excess fuel is
bypassed through the fuel pressure regulator and returned through the fuel return line to the fuel tank.
