Need help with fuel gauge!

[ChargerCharlie]

I am working on my 68 Charger fuel gauge. It has correct 5 volts going out the the new sending unit, gauge works and I have 5 gallons of gas in the new tank. I have the ground strap in place have tested the wires for voltage and resistance and all checks good. The only thing is the gauge is not moving at all. I tested the gauge with 5 volts and the needle swings through full range of motion. It seems everthing is in order and functioning properly but so far, no needle movement. 

Any help or advise sure would be appreciated.

[histoy]

First I would remove the wire from the sending unit and ground it.   Have someone watch the fuel gauge when you ground the wire.  The gauge should go to full.   If it doesn't, the problem is in the wiring or the fuel gauge.   If it does go to full, then the problem is at the tank sending unit.   Hook the wire back up to the sending unit, and run a jumper from the sending unit to a good ground.  If the gauge works, then make the ground wire a permanent fix or improve the contacts for the small strap between the sending unit and gas line.   If that doesn't move the gauge, then the float on the sending unit may not be bent properly to read 5 gallons of gas as 1/4 full on the gauge.   Remove the sending unit and verify that it will move the gauge from empty to full as you manually work the sending unit.   If it does, then bend the float to make the gauge read 1/4 full when you insert it in the tank.   

We usually try to add 10 gallons to a tank and set the sending unit to read 1/2 full on the fuel gauge, when the sending unit is inserted into the tank.

[ChargerCharlie]

Histoy!
Great advice. Well written response.  I will hit it tomorrow and do what you advised.  Many thanks!

[ChargerCharlie]

One more question..

How much fuel can you have in the fuel tank and still safely remove the sending unit?

[histoy]

I would limit it to 10 gallons.   That also makes it easier to calibrate the sending unit to 1/2 tank.   You may have to bend the float level a couple of times to get it just right.