Help with fuel guage problems

[SirRobyn0]

so i pulled the switch out of the harness and tested the wiring harness by jumping it. While it was unplugged the guage went to full im guessing because the circuit was open. when i tested them it seemed like it would show the correct guage reading only sometimes and other times it would get pegged to zero. do you think the switch is what needs to be replaced?

You might have a gauge problem then, read on to see why I think that. Or both the gauge and the switch could be an issue.

One more test.

Take the wire that leads to the gauge, turn the ignition switch on. With that wire loose not contacting anything the gas gauge should shoot past full to about the 3 o'clock position. The connect it to ground, with it grounded the gauge should read empty.

If the gauge fails to make it to either position then the gauge has an issue. There is a resistor on the back side of the gauge that should be replaced if you replace the gauge. If it goes bad it can cause odd gauge readings, like suddenly dropping or gaining 1/8 - 1/4 tank is common, with a bad resistor. It's just good to do them as a pair.

You symptoms to me though don't fit with a gauge issue, or gauge only issue, but if it fails to reach empty or 3 o'clock past full then it's bad for sure and you should replace it. If the gauge passes the above test then yes I would replace the switch.