How to Wire a Fuel Pump Relay

To wire an external electric fuel pump relay, it will take a small amount of planning. Locate a position for the relay to be mounted near the battery for convenience and ease of wiring. The relay should be a 30-amp relay and a 30-amp in-line fuse is necessary. The fuel pump can be grounded to the chassis. The switch for the interior does not need to have a high amp rating since a relay is being used.

Things You'll Need

  • Phillips screwdriver
  • Common screwdriver
  • Roll of 10-gauge wire
  • Roll of 16-gauge wire
  • Switch
  • Assorted connectors
  • Attach the 10-gauge wires--one wire goes from the battery positive cable to the 30-amp in line fuse and then to the relay. This wire should have a 16-gauge wire in the connector with the 10-gauge at the relay. The 16-gauge, along with one more 16-gauge the same length, should run into the interior to the switch.

  • The 10-gauge from the battery gets connected with a yellow 10-gauge spade connector to the B+ terminal of the relay.

  • Connect one end of the 10-gauge wire with a yellow spade connector to the ACC terminal on the relay and run it back to the fuel pump. Attach it at the pump with a yellow butt connector. Attach the second wire from the switch to the relay SW terminal with a blue spade terminal.

  • Attach a 16-gauge wire to the GND terminal of the relay with a blue spade terminal and the other end to a good ground. Secure the wire with wire ties along the frame all the way to the back. Make sure the wire does not come into contact with anything sharp or hot.

  • Attach a length of wire with a butt connector to the light in the switch and to a good ground. Attach another wire to the red positive wire on the switch to the fuse block ACC fuse.