fuel gauge and......

Wanted someone else to pull their hair out for awhile.
Here's the problem, 98 c/k 1500 4x4 305 vortec, fuel sending unit or wiring problem but where do I start. I pulled the tank off and checked the sending unit and got a variable resistance reading. So that's working. Checked fuses all over every thing is ok. Went to dealership and talked to a chief techy and he said to dump a whole bunch of injector cleaner into the tank because of build up on the metal strips of the sending unit? Is this beleiveable B.S. or is there another solution. Just trying to avoid the $900. repair bill.

it's "seams" possible,, did you check to make sure the wire is able to
send to the gauge (wire break/short)

Did you also check to see if the ground wire on the rear of the frame is good. The gauge in the cluster sends power through the sender and acording to the level, diferent voltage is sent to ground. If you got a variable resistance, the sender is working. My guess is that the loop is broken somewhere. Your gauge probably reads over full all the time. If you known the wires going in to the sender one should have power( some where around 5 volts) and the other should be ground. If there is 4 wires in the connector, 2 controll the pump and 2 control the sender. Not sure of the colors, but With the key in the run position, out of the 4 wires, one should be 12 volts, one should be 5 volts, and the other 2 should be ground.

I think I can find a wiring diagram, I had one once, but have misplaced it right now. I will look for it.

A tech guy told my to bang on the tank below the fuel pump while turning the key on and of and that got it started

I sent you a p.m. requesting your e-mail so I could send you the diagram...