Quote Originally Posted by DMCMW Dave View Post
In DeLorean03's case he is planning to run a hot wire from the RPM relay to the pump. That is probably 10-12 feet of wire. If he were to run a dedicated neg wire back to the bulkhead, that would be another 10-12 feet so he could calculate based on about 25 feet total length of circuit. Easy to figure out.

His ground path will probably be another wire connected to the front frame at one of the ground points (bypassing the inertia switch - save that for another discussion). The ampacity (current carrying capacity) of the return path (the frame) is not an issue at all, but the resistance of that ground connection and the connection from the frame to the battery are a bit more difficult to determine.
Based on this and other posts I've read, I feel confident that 16 GA should be sufficiently adequate for what I am planning on doing. The wire to the RPM relay looks to be very, very close to 16 GA - if not an exact match. There's no way the stock purple/white wire is 12 GA. I might be able to go up to 14 GA. The uninsulated female connectors I retrieved for the RPM relay can handle 16GA; 14 GA I don't know about.

I am planning to use 10-12 feet of wire going to the RPM relay and I would guesstimate 3-4 feet going to the horn bracket.

Where does the RPM purple/white wire run through the car exactly ? I know it goes from the RPM relay --> windshield washer bottle connector --> fuel pump. That seems WAY longer than what I plan on doing. I plan on going from RPM relay --> center console --> across from psgr side to drivers side through the driver's footwell --> up the fuel tank to the pump.

If I have to go get 12 GA wire and uninsulated female disconnects, that's fine. I just can't help but wonder why I should when it looks like 16ga factory stock wiring from 31 years ago seems to work just fine (short of blowing fuse #7).