I read that it's possible you knock the float ball loose from the wire clip on the float arm. That could be fun to retrieve if it made it outside the circular baffle bowl.

In this case, the arm is on the bottom. The resistance is through the wire wound resistor would be very high. This would make it show an empty tank and make you think it's not sending.

The float arm raises a tiny contact arm inside a case its attached to. It varies the resistance. You should always have resistance.

If you are grounding the gray wire all the current available from the gauge circuit warms up the needle to show full. So we know it works.

What you need to do is take one lead from an ohmmeter and place it so its current goes though the wire from the sender that connects to that gray wire.
The other lead of the ohmmeter will have to read the other side of the resistor. This should connect on to a grounding wire from the sender or placed on the base of the sender.
Double check your grounding circuit.

You can play with the old sender. It can do one more thing for you and that's show you how it works.

In either position of the float arm you must see some sort of reading of resistance.
High number means the ball or arm is very low. It's off or you are out of gas.


In rare cases the arm could have gotten knocked or wiggled off kilter upon installation. The float arm is rather long but the distance across the inner case is no more than an inch or two at best.

If the float arm is below or higher than some limiter arm stops, small tabs on the gauge case-inside, there will be no reading. The contact arm is not touching the "resistance wire" winding.

You will have to remove the sender up high enough to observe that the arm is swinging between those two tabs.
And of course, see if the ball is on the wire in the proper direction.

Hope this helps you get a diagnosis and fix.

Phil

So it's possible it is hung up or really too far down past a tab.