Fuel Pressure Regulator: Description and Operation

Fig. 18 Pressure regulator:

The fuel pressure regulator maintains a constant fuel pressure to the injectors, Fig. 18. The spring chamber of the pressure regulator is connected to the intake manifold to maintain the fuel pressure at 36 psi higher than the pressure in the manifold. When the difference between fuel pressure and manifold pressure exceeds 36 psi, the diaphragm is pushed upward, allowing excess fuel to return to the fuel tank.