12v fuel pump wiring

Discussion in 'How To' started by vanorak, May 5, 2015.

  1. Here's a good way to wire up a 12v fuel pump using two Bosch type 4 pin relays. This allows the pump to receive a strong 12v supply when cranking the starter to prime the carb (s) and when the engine is running. Should the Alternator pack up for any reason (eg. shipped/broken belt) the pump will stop working.
    Relays, cable and fuse should be rated according to the current draw of the fuel pump...

    As many 12v pumps 'push' fuel, rather 'suck', it's a good idea to mount the pump as close to the fuel tank outlet as practicable. This also allows you to keep cable runs short...relays can be mounted on the firewall, or wherever convenient...

    Disconnect the battery +ve before you do anything else....
    • run a fused +ve supply from the large nutted stud on the starter solenoid to terminal 30 on each relay

    • run a +ve feed from the opposing nutted stud (or the spade terminal 50) to terminal 85
    • join the 87 terminals on both relays with a jumper and then to the pump
    • Inline fuses can also be fitted between the Alt. D+ supply, and the +ve fuel pump supply

    Remember to fit an inline filter before the pump
    Last edited: May 6, 2015
    Bertiebot likes this.

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