My fuel gauge isn't working properly I got an 05 2500 started a couple weeks ago I know I had a quarter tank and when I got up for work started the truck told me I was three-quarters full I filled up after work went to full then drop to empty. Then all the sudden it shot up to full and I got 400 miles on a quarter of a tank it's not dropping below 3/4 put in a new sending unit and it's still doing the same thing any other suggestions