System Description

The Powertrain Control Module (PCM) will energize fuel pump relay for 3 seconds when ignition switch is turned to ON position. The fuel pump will operate and pressurize fuel system when fuel pump relay is energized. PCM receives ignition system reference pulses when engine is being cranked or when engine is running. PCM will continue to energize fuel pump relay as long as PCM receives ignition system reference pulses. PCM will de-energize fuel pump relay when ignition system reference pulses are no longer detected. The fuel supply system delivers fuel to fuel injectors at a controlled pressure. Controlled fuel pressure is 39-45 psi (270-310 kPa) when fuel pump is energized and engine is not running. Controlled fuel pressure is 30-37 psi (210-260 kPa) when engine is idling at normal operating temperatures. Fuel pressure regulator maintains correct fuel pressure at all times by returning excess fuel to fuel tank.