<VV> Gas Gauge Issue

[Charlie Davies]

A while back I posted about a gas gauge issue.  Well I need to report that I'm at my wits end on this.

Background
The gauge was registering empty on a full tank.  Drained tank. Removed sending unit.  Float was full of gas.  It had a pin hole leak.  Ordered new float.

Now
Verified new float had no leaks.  Installed new float. Reinstalled sending unit.  Refilled tank. Gauge starts showing some level, but eventually drops to just above empty.

I am absolutely 100% certain that the new float is void free.  I am certain that the wiring is fine.  While the gauge was out of the tank, I connected it to the existing hot wire and attached the ground wire to the same ground point.  I manually  operated the sending unit, simulating empty to full range and the gauge registered as expected.

I have actually gone to the trouble of attaching a piece on fishing line to the sending unit and run it out the filler neck.  This allowed me to pull the float up and down before adding gas and the gauge would register from empty to half full when I pulled on the line.  I have been through this process at least three times.

Is it possible that the sending unit is defective now?  It is a Clark's unit I purchased about 5 years ago, along with a new tank.

TIA
Charlie Davies