I had the same issue replacing my fuel filter on my 96 5sfe. I was checking the fuel pressure (long story) anddecided to swap filters while I was at it. First time, fuel leaked. Tried again, leaked again. Third time I loosen the bracket that hold the filter to the frame so the filter would have some play while I was lining it up- I figured I had thread it wrong and was not getting a tight seal- having play in the filter helped me get it seated properly. Once I had it hand-tight, I gave a turn with the wrench, tighten the bracket back up, then REALLY tighted the thing, to the point I almost thought I was going to break it. It hasen't leaked yet- knock on wood. Good thing, too because I already tossed the original...
