Fuel Pressure Regulator

Fuel pressure regulator maintains constant fuel pressure to injectors. When the difference between fuel pressure and manifold pressure exceeds 36-50 psi (2.6-3.5 kg/cm² ), the diaphragm is pushed upward, and excess fuel is fed back into fuel tank. A vacuum-operated diaphragm inside the regulator maintains fuel pressure at a specific range. This allows for changes in engine load.

At idle, intake manifold vacuum is high, causing diaphragm to be pulled up, thus reducing fuel pressure. When throttle is depressed, intake manifold vacuum decreases, and regulator spring overcomes manifold vacuum. This causes fuel pressure to increase.