I know this is a beaten subject, but my problem differs from most. The fuel tank capacity according to the Ford owners manual is 17 Gallons. The problem is that every time the gauge gets to E or when the low fuel light comes on, we only have to add 14 gallons to fill it up. The thing will not hold one drop more than 14. All this time I thought we had a 14 gallon tank. The gauge is off 3 gallons if i am right on the capacity. Would the sending unit be the culprit. Anyone???