Using 12 AWG fuel pump wire as relay trigger.

[aarvig]

So I’m going to run an Aeromotive fuel pump that's requiring 10 AWG wiring with my Holley Sniper setup. Would it be OK to use the 12 AWG wire coming from the power side of the relay as a trigger for a second relay that’s wired directly to the battery and powering the pump?
The individual I spoke to at Holley seems to think it would be fine, but I just wanted to see what the brain trust thinks.
The primary reason for doing this is that my battery is located in the back of the vehicle and I would have to rewire the existing relay And run 10 AWG wire about 12 feet through my car to get to the pump. Additionally, the power wire for the Holley Sniper is only 12 AWG. This pump requires a power wire that is 10 AWG.

[GPatrick]

You can use the large blue fuel pump wire from the relay to trigger another higher-amperage relay/circuit. You can also use the small blue wire at the fuel pump relay as a ground trigger for your new relay and eliminate the Holley relay entirely. Since the small blue wire is a ground trigger from the Sniper you must ensure that it's routed away from high current wiring and ignition wiring to avoid an introduction of EMI/RFI.

[AndyF]

When I do a Sniper install with the battery in the trunk, I remove the Holley relay and then extend the thin blue trigger wire to the trunk. The thin blue wire is a ground trigger, so you have to wire the new relay in the trunk backwards. Then the power side is shorter and doesn't run the length of the car.

[andrewb70]

^^^ This. Andrew

[Danny Cabral]

Yeah, good post AndyF. Good clear, concise explanation (fuel pump relay/trunk battery).

[aarvig]

So how is it really wired into the main harness? It looks like the red 12 AWG wire that comes from the battery continues to the 7-pin connector, but prior to the 7-pin connector is spliced with a power wire that goes through the relay. Am I correct on this? So I just remove that splice and make a solid connection there and pull the blue wire out, right? Also, there’s one group of wires running to the back of the car. The 12 AWG power wire coming from the battery, ground wire and all of my taillight wires. Would it be stupid to run the trigger wire with those to the back? Finally, when you say the relay has to be wired backwards, how exactly do you mean backwards?

[AndyF]

DC wires can all be run together in one tight bundle, so there's no problem running the trigger wire to the back of the car inside the same loom as the various battery cables, ground cables, and taillight wires. The relay trigger wire carries a very low amp signal that completes the relay switch circuit.