Fuel Pressure Regulator

The fuel pressure regulator modulates system fuel pressure before it goes to top of plunger in fuel distributor. See Figure .

During cold start operation, reduced control pressure allows plate to open farther with same airflow. This supplies more fuel (richer mixture) to injectors until normal operating temperature is reached. As engine warms up, control pressure regulator increases control pressure, causing leaner air/fuel mixture.

Bi-metallic strip in pressure regulator changes spring pressure on control diaphragm. As strip heats up, it will bend and increase spring pressure on control diaphragm. This will increase control pressure.