Fuel Pressure Regulator: Description and Operation

Fuel Pressure Regulator Cross Section:

The fuel pressure regulator keeps the fuel pressure to the injector at approximately 265 kPa (2.65 kg/cm2) higher than that in the throttle body around the injector at all times.
The pressure applied operation to chamber "A" of the fuel pressure regulator is the pressure in the throttle body and the pressure to chamber "B" is fuel pressure. When the fuel pressure rises more than 265 kPa (2.65 kg/cm2) higher than the pressure in the throttle body around the injector, the fuel pushes the valve in the regulator open and excess fuel returns to the fuel tank via the return pipe.