Yesterday my "low fuel" bell sounded and as I was showing 531 miles passed, I went in to fill up. I was only able to put in 7.7 gallons, $12.00 worth. Thinking there was a problem, I tried to top off the tank and it would not take more. When I started it up it was showing a full tank. Could this have been a computer error or fuel tank float problem? Any suggestions would be considered...