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Discussion Starter #1
Can someone tell me why when i open the cap to my gas tank, there is a large pressure behind it? I just put gas in and when I pulled the cap off, the pressure made it fly out of my hand. I cant tell a difference in drivability between when it has pressure in the tank and doesnt.
 

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I'm by no means a chemist, but I always assumed it was because the gas would get hot and expand, displacing the air in your tank as well as producing gas vapors that need to escape somewhere. So if your tank itsn't properly ventilated, when you take the cap off, out comes the displaced air as well as the gas vapors.
 

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I dont think the 78 tanks are vented like the 79 tanks, might be your cap.
 

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Yep, the 78 caps were vented, and the 79 caps were not.

Bigmorg15, you either have the wrong cap on yours, or the
vent is plugged. Change to a 78 cap, or you can drill a
small 1/8" hole in the existing cap.....
 

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Discussion Starter #6
I may do that. the cap on it now is just a solid cap. PO must of replaced it.
 
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