what i allways do is remove the black retaining clip, spray some cleaner in the connection.. Then push the line and the clip together, this will help unload the fingers,, while holding the clip end insert the tool and push the line and the tool and the clip together. then while holding the tool in the clip, pull back on the line, it should separate... ALSO there will be a lot of fuel pressure in the line unless you remove the fuel pump fuse and run the truck till it runs out of gas.. ( 5 seconds or so)... to re install you simply push the filter into the clip..
Thats really the best i can describe it...
Maybe some one else has another way of doing it..
Todd Z