rroth01

I was wondering if anyone has ever experienced this .
I have a great specimen of a Fuel Gauge the nicest one I have seen, installed in my Instrument Panel.
I am not getting a true reading and here is my question.
Once it is installed and the retaining screws are tightend I am getting a lot of needle activity.

If I tighten it down it will go beyond FULL.
If I back it off I get it to 3/4 of a tank.
Tighten it up skightly and it will bury the needle to EMPTY.

I have checked both connections at the tank.
The sending unit is brand new.
I believe just over a half of a tank full.
Thanks in advance
Ron Roth