I put a complete new wiring front to rear on the car. The plug is on the sending unit, good ground, but gauge does not move at all. Any suggestions on were to start trouble shooting?

Thanbks again,
John
Montana

Where is the needle stuck?
If way over full then the gauge is likely not getting and signal. Check the sending unit where it plugs into the trunk harness in the trunk near the filler tube.
next you can pull the tan wire off the tank and ground it. The gauge should go to empty. If it does you likely have a sending unit problem. If not then the wiring to the gauge is bad or the gauge is bad. You can ground the wire to the gauge out as well under the dash to rule out a Gauge problem. If that goes to empty then it is the harness.

J

Jearly,
The needle is on empty. I have another 68 I took this dash out of last night.
Before I pulled it out, the gauge worked. I had some gas in it , put some more in and the needle moved. The sending unit and tank are new as well.

The dash out of my vert has a bad circuit panel. It was torn bad.

Anyone?

If the guage is on empty, the sending unit wire is grounded out, could be anywhere between the guage and the tank. Anything from a bad sender to the wire being cut on a body panel.

Start by disconnecting the sender wire in the trunk. If the guage doesn't float past full, disconnect the rear body harness at the top of the drivers kick panel. If it floats past full now, the wire insulation is damaged and shorted to ground between those 2 points. If it still doesn't move, the problem is in the dash harness or at the guage.

Jim,
I disconnected the plug in the trunk and the gauge went past the full mark. Is the sending unit bad?

YES! or.... the wire from the connector in the trunk to the sender is pinched and shorted under the tank, or... and this is a long shot... but with all new wiring it is possible that the plugs for the sender and the license plate light are reveresed. Does the license plate light work normally?

You have for sure verified positively that everything forward of that connector in the trunk is good.

Jim,
I disconnected the rear harness and the needle still goes past full. I will get to the bottom of it.

Go bACK TO THE TANK! you're good all the way to that connector in the trunk!