New to the group so Hello all!
I have a 68 Camaro resto mod, been building for a few years. Noticed a few weeks ago the fuel gauge wasn't working. Found the sending unit wasn't working correctly, so bought new, test it and replaced. Gauge still didn't work. Checked cable and ground--no movement of fuel gauge needle at all. All other functions on the cluster are working. Possible bad circuit board? Bad gauge? Also wondering if I may have put it together incorrectly. There is a piece that looks like an insulator and another that looks like a metal jumper--not sure if I have them in correct order when installing...the manual doesn't specify--so am hoping someone has a diagram or pic of the way it goes together. TIA

 

You might try a search on this site and read what comes up.
Ensure you have a good ground everywhere.

 

Very hard to determine electrical issues on line since there can be so many different problems. Get a hold of the wiring diagram online and a volt tester. Trace back and test all your connections. Like Everett said, check all your grounds, make sure the wire is good and wire brush them if needed. Especially the one at the gas tank. If all works, then could be the gauge on the dash cluster?