fuel gauge issue.

[78 k20 8,400 gvrw]

This is starting to piss me off. When I got the truck the fuel gauge worked fine on both tanks. While I had the heads off doing the head gaskets I found some wires that were rubbed through where they go through the exaust tube. The wires were to the starter and fuel gauge, so o fixed the starter wires and ran them through the exaust tube. I decided I would fix the fuel gauge later so I tied it up out of the way so it wouldn't short out.

So recently I tried fixing the wiring to the fuel gauge and I rerouted the fuel gauge wire to where it didn't have to go through the exaust tube. I soldered and heat shrank the connections I made and got in and turned the key on. It still exactly the same pegged above full. So I figured I'd check the grounds since I just had the tanks down replacing the fuel lines. Grounds are good and have a good connection on both tanks. Wiring to the sending unit is fine all the way to the fuseblock in the fire wall. I checked the fuses and they are fine and all of my gauges work. I tried swapping my gauge cluster out with a spare I had laying around, same thing. This is driving me nuts, anyone know what I should try next?

[78 k20 8,400 gvrw]

Just crawled under it and ran a ground pin into the wiring going to the tank and my gauge went to empty. I must have dislodged a wire on the tank when I pulled it

[78 k20 8,400 gvrw]

Just FYI to anyone searching fuel gauge issues.
My problem ended up being where the gauge side of the wire that slips over the connection for the sending unit was the culprit. I cleaned it up and had to play with it a bit until the gauge started to register then I reinstalled the tank and its working perfectly.
When I pulled the tank it looked clean, but it wasn't getting connection.

Word to the wise, make sure your fuel gauge is working before you bolt the tank back in.