[lennyrebel]

Originally Posted by lamric

...That and the fact that the nozzle is in air and not fluid until the tank is full. There's no way you could pull enough vacuum down the fuel filler to trip the nozzle at engine idle.

http://www.straightdope.com/classics/a1_263.html

I guess your failure to understand how the charcoal canister and assorted tubing relates to the filler neck adds to your misunderstanding. Because I don't want to see a massive explosion I guess I'm the fall guy. No understanding some peoples logic.