Just did mine, 1998 explorer fuel filter, what a PITA, another reason to shoot someone at ford.
There are 3 metal flaps in the line, and even the rubber seals seem to be tight, so it takes a lot of fiddling, then pop – its free. At lease I didn’t skin my knuckles.
Anyway, I think the trick is to use a full circle tool, not the wedge style one (that came with the filter...) As others have said, push the line into the tool, then the tool into the line, then rotate it about 180 deg, then wiggle the line from side to side whilst still pushing on the tool.
Some added tips:
Relieve the fuel pressure at the shrider valve ( about 1/4 of a pen of fuel will shoot out). No need to try and figure out where the relay is or run the car.
Take the fuel cap off – just in case – while your pulling and pulling you want to be sure you’ve done EVERYTHING – trust me.
Rotate the fuel line around on the pipe for a while to free up the seals. And push it in and out 1/16 inch a few dozen times.
In order to do this, you MUST use both your hands, one on the line wiggling and pushing a little towards the tool, and the other on the tool pushing down inside the line end.
Some have said to use a screwdriver and lever it in, I tried that with no luck. I think you just have to pray.
-Ralph