Gas cap
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6th Gear
Joined: Feb 2024
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Gas cap
I got a new gas cap that said it was vented for my 1950 Ford truck but when I went to the gas station, I took the cap off. It really made a serious Sound of all of the pressure escaping. Just wondered if that is normal or if it means that that gas cap is not vented Like they said it was.
Hotshot
Joined: Oct 2009
Posts: 16,188
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From: Burbank, WA
Depending on your location, altitude, climate, temperature, it is not unusual to have some pressure build up in the tank, especially if you're empty and there's room for a lot of fume buildup. On a hot and/or humid day, it is not surprising and I've had it happen to me. This is not to say you may not have an issue. You can always test the cap to be sure it is venting.
Parts Nerd Extraordinaire
Joined: Sep 2010
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From: Western NY
Be aware that some vented caps work one way, as in making sure the tank isn't under vacuum. Just as an example, looking at this generic vented gas cap, it has a warnig because the tank may become pressurized: https://www.napaonline.com/en/p/THM7031220
Lead Driver
Joined: Aug 2006
Posts: 8,094
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From: Brentwood, TN
First question...was it positive pressure escaping or was is a negative vacuum, ie, air rushing in?
If the cap is not allowing air to come into the tank to replace the void left by gasoline being used, then there is a real chance that the tank will collapse. Gotta have a good fuel pump for this to happen.
As for pressure in the tank, that's always a possibility but that situation would be caused by circumstances as Wayne has described.
If the cap is not allowing air to come into the tank to replace the void left by gasoline being used, then there is a real chance that the tank will collapse. Gotta have a good fuel pump for this to happen.
As for pressure in the tank, that's always a possibility but that situation would be caused by circumstances as Wayne has described.
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6th Gear
Joined: Feb 2024
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So I understand what you guys are saying correctly is when it says it’s a vented gas cap that means it’s allowing air to come into the tank but not necessarily letting pressure out of the tank. Am I on the right thought process thanks for all your guys insight.
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awatchman
1961 - 1966 F-100 & Larger F-Series Trucks
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Jul 9, 2023 09:55 AM
