Wire gauge for fuel pump

[99tantj]

I'm running a stock 5.7 ls1 in a TJ. I'm installing a new in tank fuel pump....aeromotive sealth 340. Aeromotive tells me I need to wire it with
10 gauge. I think this is a little overkill for a stock ls1. I have a jegs fuel pump relay harness like this http://www.jegs.com/i/JEGS/555/10564/10002/-1, but it only has 12 gauge going to the pump. The wire to the battery is 10 gauge. Do you think I would be alright with 12 gauge going to the pump? If not, can I splice the 12 gauge coming off the relay harness with 10 gauge, or would the short section of 12 gauge that's left on the harness limit me? The wires that are in the tank going to the pump are not very large, maybe 16 gauge.

Thanks

[TorqueRanger]

Originally Posted by 99tantj

I'm running a stock 5.7 ls1 in a TJ. I'm installing a new in tank fuel pump....aeromotive sealth 340. Aeromotive tells me I need to wire it with
10 gauge. I think this is a little overkill for a stock ls1. I have a jegs fuel pump relay harness like this http://www.jegs.com/i/JEGS/555/10564/10002/-1, but it only has 12 gauge going to the pump. The wire to the battery is 10 gauge. Do you think I would be alright with 12 gauge going to the pump? If not, can I splice the 12 gauge coming off the relay harness with 10 gauge, or would the short section of 12 gauge that's left on the harness limit me? The wires that are in the tank going to the pump are not very large, maybe 16 gauge.

Thanks

You should be ok but I would redo everything in 10 ga and if you go with 12 ga then I would run it for a while and keep an eye on the harness and make sure your not frying the harness,

[billy bones]

The factory only used 16 or 18ga from the relay to the pump. So 12 will be fine, especially on a short chassis. For a stock 5.7 you wont be running enough fuel pressure (amperage) to warrant a 10ga circuit.

If you splice together a 10ga and a 12ga wire the circuit will will be limited by the 12ga section. Its the weakest link in the chain. Better to run the same size wire the entire length of the circuit, with no splices, and crimp on new terminals as needed.

[usmcdoc14]

Your fuse should always be the limiting factor of your wire and the smallest wire that is connected after that with no additional fuses.
So you are fusing for under the ampacity for that 12ga wire.

Anything bigger than 12ga after is moot as you are still fusing your weakest point.

So either run all NEW 10ga and fuse accordingly or run 12ga from your existing and fuse accordingly.


Your aeromotive sealth 340 has a max amp draw of 19A at 100psi according to the owners manual. a GENERIC wire size of 12ga is fine for 10' run or less, anything longer you should up the gauge. (this is a generic statement based on average ampacity of wire size, look up the CORRECT amp rating for YOUR wire brand if you feel you are cutting it close)
And fuse it to 20A

[billy bones]

True. I forgot to mention the fuse. Was just talking about the wire from the relay to the pump.