Fuel Pump Relay: Description and Operation

Fuel Pump Relay (Circuit Open Relay):

The fuel pump relay (circuit open relay), located inside the center console and under the dashboard, supplies power to the fuel pump, when energized.

The relay has two separate hold in coils. One for starting (cranking) and one for running. During engine cranking, current flows through the start coil to ground, energizing the relay. The run coil gets power from both the start signal and the "IGN" terminal of the ignition switch, at relay terminal "B". Voltage is present at this terminal when the key is in either the "start" or "run" position. The run coil, however, does not energize until the circuit is completed to ground by the fuel pump switch in the air flow sensor. When the engine is being cranked or is runing, air entering the engine deflects the air flow sensor flap and the fuel pump switch closes, energizing the fuel pump relay.