Well tonight I just figured out that the 88 F250 is rated to hold around 38 gallons of fuel. Thats 19 gallons per tank since it has two tanks. Well when I fill it up it takes about 12 gallons per tank totalling 24 gallons. I fill up when the fuel gauge reads E. So what I'm getting at is the fuel gauge isn't reading correctly. The gauge has had issues in the past but I has since been fixed but now tonight I figure it's not accurate. What could I do to fix this? New sending units or are they adjustable?