Here's a picture of the new Andair one way check valve I installed in the fuel return line coming from the engine. Without this in place you can still get fuel flow forward even with the selector off since the return line back feeds from the gravity head pressure. It's easy to put this in place (got the tip from John M at the factory as they use them on the LSA models) the only downside is it's a bit pricy! but then what's not in this game.