Both fuel lines are under pressure, and remain so, the pressure does not drop off on its own (unless something is wrong). Once the pressure is released, and the fuel is emptied from the line, no more fuel will be present until you turn on the key. Both lines will have fuel until it is drained, they each hold about a 1/2 lid full of fuel from a spray paint can. An EFI system is under pretty high pressure. If you cut the line, it will spray out hard and fast then be done. You may be able to catch the gas with a drain pan, but wrap a rag around the cut point so it won't spray in your face. Gene