Best Way to Syphon...Ever.
Just saw this thread and thought I'd chime in. The BEST way to syphon fuel out of a tank is this:
Place a hose in the tank, and the other end in a container that's lower than the tank (don't just put that fuel in the ground! - if it's old, sell it on Etsy as 'vintage'). Now just make a seal around the opening of the tank (with the hose sticking out of it) using your hand (takes a few tries to get it right), Then just blow in the tank. The pressure will force the fuel up the hose and as soon as it starts to flow you just stop blowing. The harder you initially blow in the tank, the faster it will come out. Of course you must take into account the laws of fluid dynamics and the Hagen–Poiseuille equation, and know that it won't actually come out at lightening speed, but you get the idea.
I've used this method 100's of times on bikes and boats. (easiest way to fill your boats fuel tanks when all you have is jerry cans.)