The tool shown does NOT apply to these connectors. It is for spring-lock connectors used elsewhere, but not on the fuel tank lines on a return-style Contour.
By a stroke of irony, I just worked on this yesterday and had the same problem. A SEARCH here indicated that the lines would come out once the tabs were released (I used pliers for that) but would take considerable force to pull.
Like the original poster, I was able to move them a few millimeters by tugging on them with pliers, but no more. Got frustrated, had lunch.
After lunch, I grabbed my 20 oz framing (straight claw) hammer and a regular 16 oz curved claw hammer. I used the smaller hammer to tap the claw of the larger hammer into the small gap I had made previously making certain the locking ring did not engage. A quick pull on the hammer handle and the line popped right out. Repeated for the other line.
Now, I just need to get the filler pipe disengaged so I can fully drop the tank... That one is being a real PITA. Damned P0442 leak caused by a leak at the filler pipe seal...and emissions are due this month still!
Steve