I have a 76 FJ40 and I have an aftermarket RCI fuel cell and sender. I filled it up earlier in the week and there was just about 5 gallons of fuel or so in it and it was reading about 1/2 ot 3/4 of a tank. The thing is, the tank is 19 gallons. Something isnt right at all. Yesterday I filled the tank right up as much as it could hold and it read totally empty. I have no possible idea what it could be, its almost like its reading backwards or something. Help is much needed and appreciated.