Howdy Bill
Them gauges work off of OHMS Seems like the gauge is looking for different ohm readings than you are offering.
You may have to fill the tank and then check the ohm reading at the gauge.. Then with the proper resistor in line the gauge may start working closer to properly again.
I used to know what was needed but have forgot over the years.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist