wow... umm.... that's a thinker. do you have a shop manual of some kind? if so, it may explain how to check it for a leak. i have no idea. i hope someone can give you a better idea than me. maybe try this. remove the rear seats. check around where the top of the fuel pump is located. perhaps look for a leak. maybe get the car on a lift and check under and all around the tank for leaks or holes or w/e. maybe someone else will have another idea.