Post 1 does not mention a metal fuel line.
Since I deal with diesels all the lines are plastic, but many of the connections use a copper or brass olive.
The razor blade is to cut through the plastic line just behind the olive.
Obviously, this is not applicable with metal lines.
Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)
"What's with this death wobble, Uncle Douglas, I can't keep it in 1 lane?"
UD: "Just Power through it man!"