Could possibly be the o rings have gone bad on the drain valve. I just replaced mine recently because i was leaking a lot of diesel fuel. i crawled underneath and it was coming from a small hose near the passenger side.i traced it back and found where the hose went to. it turns out my o rings in the drain valve were bad.
hope this helps
Michael Kallam
i ordered my orings from dfuser.com. they have them fairly cheap but you may be able to check with ford they may have some at the dealership