Pressure regulator
The pressure regulator is mounted on the end of the fuel rail.
The regulator maintains a constant differential pressure between the fuel and the intake manifold. In this way, the amount of fuel injected can be determined solely by the electromagnetic injector timing.
The pressure regulator is a diaphragm-controlled overflow valve set for 3.0 bar. It consists of a metal housing divided into two chambers by a press-fitted diaphragm. In one of the chambers there is a spiral spring that presses against the diaphragm while fuel flows through the other chamber.
When the preset pressure is exceeded, a valve controlled by the diaphragm exposes an opening to the return line through which superfluous fuel can flow back to the fuel tank.
The pressure regulator spring chamber is connected to the intake manifold after the throttle body via a hose. This means that the pressure in the fuel system is affected by the absolute pressure in the intake manifold and the drop in pressure across the injectors is constant at each inlet pressure.