View Full Version : 10ga all the way to fuel pump?

06-06-2016, 10:14 PM
You guys that have upgraded the fuel pump harness wiring... What is the best way to get the 10ga wire through the top of the hanger assembly. I tried searching for pics but I didnt have any luck tonight. It seems like I remember seeing someone use bolts and nylock nuts that overheated and melted the nylon. I thought I also remember seeing someone passing the wire straight through using grommets. Any suggestions?


06-07-2016, 09:09 AM
Don't make it harder than it has to be. No need to actually run a 10ga all the way to the tank. use the original wiring to activate a relay that runs 12v right from the battery using that 10 ga wire you mentioned. I put my relay on my 95 SC near the bottom of the DS sale panel which is where I found my wiring sending voltage to the fuel pump. Simply use that voltage to activate your relay to send the full 13.5 volts to the fuel pump from the 10 ga wire you will need to run from the battery.

Make sense?


06-07-2016, 01:10 PM
Yeah I understand how to wire it up. I am curious if most people splice in the new power feed supplied by the relay into the harness right before the tank, or if they run the wire through the top of the hanger assembly and go all the way to the pump. I'm replacing the pump with a 340lph, so I will have it apart anyways.

06-07-2016, 02:10 PM
Mine is spliced in before the harness connection not the pump connector. So that you can disconnect the harness when dropping the tank.

06-07-2016, 04:33 PM
Yep same way.

06-07-2016, 04:48 PM
Electrically, there is no real performance advantage in taking it all the way to the pump. The wiring upgrade is mainly supposed to remedy the voltage drop problem, where any up-size reduces voltage drop.

The only issue though is that the Aeromotive fuel pump also requires that the wire handle higher current than factory. I'm not putting my neck out there, but my opinion is that since the remainder of the wiring is in the tank, ambient temperatures will be lower and therefore the smaller wiring is okay.

DO make sure that there is plenty of dielectric grease on the sending unit connector though!!!!

I suspect that the old grease oftentimes dries out and allows a little corrosion and arcing to occur, which generates heat and can lead to fires. Any existing problems will be aggravated with the higher output pump.

I also think that it is overall safer to not try to add any new connections through the sending unit, since a little time and moisture could create a major safety hazard.

06-07-2016, 04:49 PM
Just put one of these on there....................:rolleyes:

06-07-2016, 04:52 PM
On mine, I took the 10ga all the way to the sending unit/pump power connector. This was not easy and probably not worth the extra trouble, but for some OCD reason, I like to disassemble Ford connectors and repin / resolder them. :o

David Neibert
06-08-2016, 02:51 PM
On my 91 SC we ran a 10 gauge wire from the alternator output to a 40 amp relay mounted beneath the rear seat. We used the stock power wire for fuel pump to trigger the relay. From the relay we also ran 10 gauge wire to the pump hat and attached the wire with ring terminals to the modified top hat that has studs installed where all the stock plug on terminals were. On the inside of the pump hat, both pumps were attached to the terminals using the stock size power and ground wires (dual 255 high pressure). We also attached a 10 gauge wire to the ground terminal on the pump hat and bolted the other end to the body of the car. Once all the wiring was attached we covered it in clear silicone caulk to keep water out and to keep anything from coming loose.