[moehoward]

Think of the gasoline you keep on hand for your lawn mower. It's in a closed container, and after a few minutes, or hours depending on the temperatures, it has a pressure built up.

Only if the outside temp is warmer than the inside temp.

[Balding_Eagle]

Only if the outside temp is warmer than the inside temp.

Your lack of common experience is showing. Give me a day or two (like most I have a life out FR) an I'll have a more technical answer.

[Balding_Eagle]

Just a quick experiment anyone can try:

Take a small amount of gasoline and place it outside, in the shade. It will evaporate, and the speed of the evaporation will depend on the air temperature. What the evaporation proves is that the vapor pressure of the components of the gasoline are higher than the air pressure.

This has got to be about General Science II level stuff. What I learned in 11th grade, and today they learn if they go for a PhD.

The way car (and aircraft) manufacturers counter that vapor/air pressure differential is to provide a tank that is prssurized. The tank pressure is determined by, amoung other things, the altitude of the tank.