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Discussion Starter · #1 ·
I'll just throw this one out there for anyone to answer. If the sun is beating down on a very hot summer's day against the side of the car where the fuel filler port is located behind the fuel door and the fuel tank itself is only partially full, could enough inside pressure build up to make it difficult to twist off the fuel cap? It happened to me on the way home from a car show on Saturday when I stopped to fill up at a service station. I simply could not get a tight enough grip on it to remove it and had to get help from a much younger and stronger man who came to my rescue!
 

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What car and year do you have ?
 

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Discussion Starter · #3 ·
1963 Impala 4door hardtop. The gas cap is not original, but aftermarket.
 

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I'll just throw this one out there for anyone to answer. If the sun is beating down on a very hot summer's day against the side of the car where the fuel filler port is located behind the fuel door and the fuel tank itself is only partially full, could enough inside pressure build up to make it difficult to twist off the fuel cap? It happened to me on the way home from a car show on Saturday when I stopped to fill up at a service station. I simply could not get a tight enough grip on it to remove it and had to get help from a much younger and stronger man who came to my rescue!
I have a 65 with a new fuel tank. a while back I thought I noticed pressure or sometimes vacuum, depending on the temperature, when I removed the gas cap. I thought it may have been affecting the ability for the engine to idle well, after it had been running awhile, also. I put my mouth on the filler tube and blew. pressure blew back in my face, when I took my mouth off. I disconnected the rubber hose from the tank to the vent and blew the vent out with compressed air. A plug of rust and crud blew out. When I blew in the filler tube again, I actually still had pressure build up, but I discovered if I just held the pressure for a little while it would mostly dissipate. I would check your vent tube to see if there is any blockage.
 

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Discussion Starter · #6 ·
I have a 65 with a new fuel tank. a while back I thought I noticed pressure or sometimes vacuum, depending on the temperature, when I removed the gas cap. I thought it may have been affecting the ability for the engine to idle well, after it had been running awhile, also. I put my mouth on the filler tube and blew. pressure blew back in my face, when I took my mouth off. I disconnected the rubber hose from the tank to the vent and blew the vent out with compressed air. A plug of rust and crud blew out. When I blew in the filler tube again, I actually still had pressure build up, but I discovered if I just held the pressure for a little while it would mostly dissipate. I would check your vent tube to see if there is any blockage.
Thanks! I'll check that.
 

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Discussion Starter · #7 ·
The '63 require a vented cap.

Pete
Thanks! I thought my after market cap was vented. I'll have to give it a more "forensic" inspection. The only reason I thought inside pressure from heat buildup was the culprit is because when I next stopped for fuel the outside air had cooled considerably and I had no problem at all in removing the cap.
 
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