MX-5 Miata L4-1597cc 1.6L DOHC (1992)
Fuel Pump Relay: Description and Operation
Fuel Pump Relay (Circuit Opening Relay)
PURPOSE
Supplies power to the electric fuel pump. As a safety feature, the relay is only energized when the engine is running or being cranked by the starter
motor.
LOCATION
Under dash next to steering column.
OPERATION
Relay has separate hold in coils for starting (cranking) and 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 "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 airflow meter. When the engine is being cranked or is running, incoming air deflects the airflow meter
flap and the fuel pump switch closes, energizing the fuel pump relay.
CONSTRUCTION
Relay has separate hold in coils for starting (cranking) and running.
