Shadow L4-135 2.2L SOHC VIN D FI (1992)
Fuel Pressure Regulator: Description and Operation
Location
Mounted on the top of the throttle body.
Operation.
Maintains a constant 39 psi (270 kPa) across the fuel injector tip.
The regulator uses a spring loaded rubber diaphragm to uncover a fuel return port.
When the fuel pump operates, fuel flows past the injector into the regulator. The blocked return port restricts fuel from flowing any further.
When fuel pressure reaches 39 psi (270 kPa) it pushes on the diaphragm, compressing the spring, and uncovers the fuel return port.
The diaphragm and spring will constantly move from an open to closed position to keep the fuel pressure constant.