Fuel Gauge Issue

[Honest Bob]

I found this video to be particularly informative.
https://www.youtube.com/watch?v=LRQU7chppLg

On my blazer I had two issues. It would work randomly and go way past full.

1. Loose fuel sender connector located in the middle of the truck (little rubber connector).
2. A fuel sender that tested bad at first, but got working with some tinkering. Ended up replacing it.

You really need to inspect every inch of the wire and clean all the connectors/grounds. A loose connection anywhere in the circuit is adding more resistance which may be causing your issue. If its going way past full that indicates a break in the circuit and can also be in the fuel sender if its not working properly.