[wilkin250r]

If your tank was relocated, that makes it a little less likely that your sending unit is bad, as it was most likely replaced at that time.

However, the test is still essentially the same. Connecting the sending wire straight to ground (zero ohm resistance) should read as an empty tank. Leaving the wire disconnected should peg way past full.

Did the gauge ever work properly, that you know of? What is the possibility the last owner relocated the tank, but never bothered to connect the sending unit line?