What I want is a vacuum/vent valve. It's a doohicky with 2 spring loaded ball checks inside. One provides venting into the tank when the engine is running and sucking fuel. The other provides air venting when the tank is being filled. The balls are lighter than the fuel, so one of them blocks flow if submerged (as in upside down). If the car is sitting in the garage, both valves are closed so there isn't any evaporation and smell. I think aircraft use these things, so maybe one of you plane builder types can point me straight.
[ December 16, 2002, 11:13 PM: Message edited by: Joe Leone aka Oldguy668 ]