One one side of the fuse, I have two 10-12 gauge red wires that both go through the firewall. Going from memory (I really don't want to split the harness AGAIN - lets face it, the car hasn’t burned down YET...until it does 😑😎
one of them goes to the starter solenoid positive terminal and the other goes to the bat post on the alternator (converted to 3g 160a as part of my EFI install). On the other side of the fuse, I have one 10-12 wire that goes to the bat post on the IGN switch. It’s the only wire on the bat post of the IGN switch. I can not only pull the fuse, but completely unhook both wires from the fuse block and I still get +12v.
If the car was still carbureted with a 1g 55amp alternator, I wouldn’t worry too much - a 10 gauge wire can handle ~ 700 watts without catastrophic side effects. Now that I have almost tripled the amperage capacity, I would like this fuse to function as intended. I have a 150a fuse in the battery charge wire, so that aspect is covered.
Any ideas on how the juice could be working “backwards” through the harness would be appreciated.
I’ll be out if town until next week, but I intend to retrace the power wires to/from the fused side when I return. Again only one wire on the “bat” IGN switch terminal and it shows continuity to the same color and gauge wire on the fused side of the 50a fuse holder.