revisit the fuel gauge and sending unit issue

kiss said

You've been through multiple aftermarket fuel sending units all with the same problem?

Since you've run a dedicated wire with no change I'd check the integrity of the ground to the sending unit.

If that doesn't fix it i'd look at the gauge itself.

Click to expand...

The wire measures 53Ωs at the sender AND at the fuel gauge. But you are correct. there is nothing left but to reexamine the grounding.

I redid the grounding. I even made it single point grounding, what does not matter at all. I thought about ground loops but that is not applicable.
Everything I did and the gauge did not change.

When I was a microwave engineer, somewhat fresh out of school, we had a term to describe this It is "FM" (******* magic)