I've had it happen once before last summer. The problem is pretty common on some of ford's other lines such as the explorer. The 'fix' that the dealerships recommend is putting in a bottle of the fuel additives every 5k or so.
Maybe there is some gunk on the unit. Sounds like the float is sticking in the down position.
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2004 Cobra, Whipple ,TH-400
Burning Corn
9.97 - 135.5