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Would appreciate any help that can be given, I've been pulling my hair out on this. I have never been good with electrical stuff, and I recently purchased a '89 Comanche with the fuel tank out of it. I hooked up the fuel tank and tried to start the truck, but the fuel pump will not prime or pump when cranking. I've cleaned all grounds, swapped my relays around, bypassed the ballast resistor by setting a paperclip between the connectors, and still have nothing. The pump works when setting the battery up directly to the pump. I set a paperclip between the 30 & 87 on the fuel pump relay, and still nothing. I checked the ground behind the tail lamp, and even cleaned it up, but still have nothing. I tested the rear lights and they work so I don't think the harness back there is part of the problem. I attempted to test voltage at the connector right before it plugs into the pump, and got 12v during the prime. I'm not sure I tested it right, so any guidance is helpful. I am getting 12v at the starter relay fuel pump ballast terminal connection. I looked at the fusible link on the starter relay fuel pump ballast terminal & it appeared to be fine, I was also getting 12.4v at the link. I'm sure I might be leaving some things out, so please ask any questions and I'm happy to answer. I'm really at a loss of what to do at this point. Any advice or guidance?

so when my truck is at idle the alternator charges around 14 volts, which is normal id say, but the problem is when i turn on my blower and headlights it drops down and charges at like 12 volts i think this is why I've been going through so many batteries recently :fs1: , any one have any ideas on why this happens? I'm thinking its a regulator issue or something along the lines, but knowing these trucks it could be a simple ground. any ideas or suggestions would be greatly appreciated, THANKS (1986 2.5l 4 speed 4x4)