Fuel Pressure Regulator
Fuel pressure regulator is a vacuum operated relief valve mounted on fuel rail. Fuel pressure to injectors is maintained at about 3 times barometric pressure adjusted for engine load conditions and vehicle speed. Fuel pressure regulator consists of a fuel chamber and a vacuum chamber separated by a diaphragm. See Fig 1 . Fuel chamber has a fuel inlet pipe and a fuel outlet pipe. Proper fuel pressure in maintained in fuel rail, also referred to as fuel distribution pipe. This ensures that appropriate amount of fuel is delivered to injectors under correct pressure. Fuel inlet pipe delivers fuel to regulator from fuel rail. Excess fuel is returned to fuel tank by fuel outlet pipe.
Vacuum chamber is connected to intake manifold by a hose. Any change in fuel pump delivery pressure or intake manifold pressure will cause diaphragm to move. This movement will maintain pressure balance between intake manifold and fuel chamber to ensure a steady supply of fuel to fuel injectors.