Fuel Pressure Regulators

Fuel pressure regulator devices are connected to the fuel rail to balance and keep the pressure in the fuel system. This keeps the injectors at a constant pressure through a spring-loaded membrane which allows the opening of the return-flow channel. 

The valve uncovers a fuel line that returns excess fuel to the fuel tank when it is opened by excessive pressure in the fuel lines. If the pressure of the fuel is less than the membrane pressure, the excess fuel flows back to the fuel tank increasing the fuel pressure at the injector.

If the pressure of the fuel supplied exceeds the spring-loaded membrane, the diaphragm retracts the valve to discharge the excess fuel and thus reduce the fuel pressure at the injector. As the pressure difference between the two sides of the injectors are balanced and constant, the amount of fuel injected depends solely on the opening time of the injectors.