900 SE Convertible V6-2498cc 2.5L DOHC (1995)
Fuel Pressure Regulator: Description and Operation
FUEL PRESSURE REGULATOR
The pressure regulator is mounted on the farther short side of the fuel injection manifold.
The pressure regulator maintains a constant ratio between the fuel pressure and the pressure in the air induction pipe. This ensures that the amount of fuel
injected is determined exclusively by the opening duration of the electromagnetic injectors.
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 a spiral spring presses against the diaphragm while fuel flows through the other chamber.
If 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 spring-loaded chamber of the pressure regulator is connected by a hose to the engine's air induction pipe or throttle. In consequence, the pressure in
the fuel system is affected by the absolute pressure in the air induction pipe, with the result that the pressure drop across the injectors is constant at all
p0sitions of the throttle butterfly.
