How do I jump a fuel pump relay of a 1988 GMC K2500 with a 5.7L to get power to a sending unit from a 1998 GMC C1500 with a 5.0L V8?
Doing a gas tank swap and the fuel sending units are completely different.
Cars & Trucks - GMC - K2500 - 1988 GMC K2500
Answers & Comments
Not sure that we are thinking of the same thing. The wires to the gas tank operate the fuel pump and the fuel gauge. The relay is used to send power to the pump and you should not have to do anything to it to get power down the wire to the pump. When you turn on the key, the relay closes and power goes to the in tank fuel pump.
The newer one has 4 wires and the old one has three. The old one used the tank as the ground connection. The newer one does not. If you go to autozone dot com and make a free account, you can put in the year, make and model of the truck and look at the free repair guides to see the electrical system diagrams.