401 Fuel Gauge or Sender Problem.

[PEU186F]

You have checked that the gauge case is earthed, haven't you, this is essential. In my experience if the sender goes open circuit and everything else is ok the guage will show full.

I have found this simple explanation of the way the gauge works very helpful, the way the guage is put together became more sophisticated but the principle remains the same

Fuel Gauge - Working or not?

Roger