To the best of my knowledge, there is no pressure in the fuel lines, but, be careful because when you remove the fuel line from the fuel pump (the line from the tank) fuel will run out of it as the tank is higher than the fuel pump. It will continue to siphon out until the tank is empty unless you block the fuel line. The best way to do that is to have a small bolt (with the threaded section cut off so that is only smooth 'shank' that you put into the fuel line) to hand so that as soon as you disconnect the fuel line from the pump, you can insert the bolt into the fuel line and tighten up the fuel-line clamp. Off the top of my head, I think that it is 6mm fuel line.
