67-72 Chevy Truck fuel gauge diagnostics 101

[jjzepplin]

Originally Posted by jjzepplin

So I went and filled it up today. Bad news. Reads just over 1/4 tank. More than before but dagnabit! And as an added bonus now it burps gas upon fillup again for some stupid reason. SHAZAM! On the other hand the new front sway bar makes it ride fantastic. Think a rear is on the way.
I did not do any testing yet but will keep you all posted.

Allrigty. Went out and tested the sender today to find it is reading 90 ohms-hmm. Went inside the cab and pull the sender wire and it reads 90 ohms- hmm. Pulled what I thought was the ground clip for the gauges and nothing happened to the gauge.
Is there more than one ground clip?
This gauge and sender tested fine out of the tank. Why would it be any different inside the tank?
The only difference I can find is the tank sender ground was a jumper wire.
I have a ground wire on the tank that previously was not hooked up but it is now.
Sound like a ground issue?