[Bounty__Hunter]

Sounds like a corrosion problem if you've had to clean some rust in the tank. The float arm moves a metal contact along a contact grid, thus transferring the position of the arm into an electronic signal. Sounds like the contact grid on the sending unit is nearly all corroded.

You can often change just the sending unit, transferring the pump over to the replacement sending unit.

I had an extra one, but I nearly bent it in half when a rock dented in the bottom of the fuel tank.