I traded messages with some folks last year concerning this same issue. My dealer has replaced the sending unit, and replaced the gauge twice (last time with a gauge from a Supra). I still have no idea how much fuel I have, even at idle on calm water. I traded in a 1976 Checkmate and it always gave me a true reading whether at idle or 45 mph. Brian....are you guys looking into this or is there something our dealers are missing? Like most other owners, I LOVE MY BOAT, but I don't want to turn a good day into a bad one by running out of gas while cruising along and the gauge shows 3/4 full.