[Tommy]

I've never seen a fuel system with a drain valve, so I'd likely use the electric fuel pump too. To depressurize the fuel line I'd leave the pump off and briefly start and run the engine. Then I'd disconnect the fuel line somewhere higher than the tank where a fitting to a drain hose could be connected (e.g., a barb fitting in a rubber hose). Put the other end of the drain hose in a gas can and turn on the fuel pump until its near full.