Fuel sending unit

An ohm meter between the sender wire post and the body of the sender ( the tube or the flat plate)

Then move the arm and watch for resistance change

The official values

Are 10 to 73

And 23 is 1/2 tank (but 1/2 is NOT 1/2 travel)


Full droop should get you in the 60-80 range

Full up should get you 5-15 range.

If those 2 are good and the resistance changes readily consistent from full droop to full up ( meaning it doesn't jump around too much)