I can not get the fuel sender to show 100% when the fuel tank is full. The sender will show 100% when you ground the contacts but otherwise shows 64% when full and goes down to 62% after running down the tank. The factory checked the signode sender for calibration and operation and says the problem is not the sender. Is there some adjustment on the gauge settings I can make? All I see us the US ir Eu setting. Would the gauge do this if it is set to EU?