Thread: Gas Cap vents
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Old 04-05-2010, 11:25 AM   #14
Roger
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Quote:
Originally Posted by MakoMike View Post
But both vents are not above the level of the fuel, that's his problem. The one vent he has now is below the fuel level in the tank, so gas "weeps" out of the vent line. Adding another vent above the fuel level is just going to force more gas out of the vent that is below the fuel level. Physics 101.
I think you need to revisit your "Physics 101" because you couldn't be more wrong. By your explanation, gas should shoot out every time he opens the fill cap since he is in effect adding a vent by doing that.

Fuel weeps out because there is an air pocket that warms, thus expanding. Since his one vent is below the fuel level, the air pressure builds up and forces fuel out. If that air pocket was vented the pressure would equal the outside air pressure and there would be nothing to force the fuel out.

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Roger
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