Ok so i just replaced my sending unit for my 56 f100 because the old one was not working and the gauge would always stay on "E". After replacing it the gauge now functions and after only putting in about 3 gallons of gas the gauge reads"full". it is the original gauges and the original type of sending unit. Heres the trivky part, the battery died and had to jump start it with another vehicle and while it was being jumped the gas gauge moved and showed that i had less than a qtr tank and once the jumper cables were removed the gauge went back to reading full. What could the problem be?