[buzzinhalfdozen]

Bill, then the sender you're using is set up backwards, the resistance empty to full is reversed switching the wires won't help (as you know now) . Most systems I work on (GM) use 250 ohms for an empty reading and 40 ohms for a full reading. Maybe see if the supplier you used has a similar unit with the resistance values reversed. I'm unaware of a way to correct the unit you have, without "flipping the card" basically taking the resistance grid and flipping it upside down so you get the needed values. Good luck. Joe