Dang gas hand

[Tntruckowner]

Ok I had to clean my gas tank out and when I put it back in my gas hand don't want to work the wire on top of the tank when I loosen it the hand goes past full when I tighten it the thing goes empty this is on a 68 C10 any help would be appreciated

[bill3rail]

I assume you are referring to the needle on the gas gauge?

[Tntruckowner]

Yes sorry I should have mentioned the needle

[AussieinNC]

When you put the fuel gauge sender back in the tank, you did make sure the float was on the unit and the float did not have any holes in it?

Also, did you by chance paint the mounting tabs in the cab when you had the tank out? The tank needs to be grounded to the cab...for the gauge system to work correctly.

[Tntruckowner]

The float is fine and the inside was not painted that is why it is so confusing I know about the tab for grounding the thing un grounded the needle goes way past full

[AussieinNC]

Sounds like the sender unit is bad...grab another known good one and swap em out...keep us up to date on progress.

I didnt mean painting inside the tank...I was referring to painting the cab where the tank mounts...at least one mount area should be a good clean ground for the tank

[Tntruckowner]

Thanks I'll work on it

[VetteVet]

Your sending unit terminal may be grounded to the tank and not reading through the resistor in the sender. Check it with a meter for continuity to the locking tab or the cab itself. If you get an ohms reading it should correspond to the amount of fuel in the tank.
I.E. 25 ohms = 1/4 tank, 50 ohms=1/2 tqnk etc.

Most likely the wire that connects to the terminal is grounded to the cab. Pull the sender wire off at the fuse panel terminal marked "fuel" and with it off at the sender terminal, check the wire to a good ground for continuity. You should get infinity, OL on the meter

[rockyrivermark]

You can run a temp wire from the fuse panel to the sender to check.
I second the thought on sender wire grounding out.