Gas gauge quit working? Help

Tony formula s said
1965 Barracuda formula s new tank and sending unit new rear wiring, harness gas gauge worked fine, now it’s not, installed ground strap on gas tank tube that jumps the rubber portion of the tube still no gas gauge worries me because it did work before any suggestions guys and gals

Ground the sender wire at the tank and see if the gauge shows full.
If it doesn’t, something about the gauge or wire from the tank to the gauge is faulty.

If it does show full when the wire is grounded, then it’s likely the sender.