929 V6-3.0L SOHC (1989)
Fuel Pump Relay: Description and Operation
Fuel Pump Relay (Circuit Open Relay)
The fuel pump relay (circuit open relay), located behind the drivers side left kick panel, 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 running, air entering the engine deflects the
air flow sensor flap and the fuel pump switch closes, energizing the fuel pump relay.
