Fuel Pump Relay: Description and Operation

FUEL PUMP RELAY





Models with air sensor wiring.
With ignition on, current is supplied to the pull-in coil which is grounded through the transistorized circuit whenever the starter is operating (terminal No.50) or the air sensor contact is open during normal running (terminal No.31B). The pull-in coil completes the circuit between battery and fuel pump via the 16 amp fuse on top of the pump relay.
To run pump with engine off for testing purposes, turn ignition on and remove air sensor electrical connector.





Models without air sensor wiring.
With ignition on, current is supplied to the pull-in coil which is grounded through the transistorized circuit whenever impulses are received from the ignition coil during starting or normal running.
To run pump with engine off for testing purposes, remove relay and bridge relay board terminals which correspond to relay terminals # 30 and # 87 with fused jumper wire or special tool US4480/3.