On my 2007 2500 I was having trouble starting my van. Once fired it would drive rough overall. No check engine lights to go by I ended up having to take it to GM to have it looked at. They came back with the news my fuel pump went out. Ok whatever. Pretty straight forward.
Get the fuel pump in and go to drop the tank. Step two is removing the fuel line and return line. Piece of cake. 2 quick disconnect fittings. Trouble is the metal style quick disconnect (of course there's one plastic and one metal) WILL NOT come off. I bought the insert, and nothing. I even bought the Matco fuel line and AC line pliers. That didn't work either. Am I alone on this? Is there some special trick or tool used to disconnecting that thing or is mine defective? ANY advice would be appreciated because right now all I have is a 2 ton brick sitting in my drive way with a plastic sleeve stuck in the quick disconnect...

 

an you post a pic of the connectors in question?
Are you sure that it not just the pinch type that you pinch and push in and then pull back to pull apart?