In my recent travels, I was driving the car in very hot and very dry conditions, in some higher than normal altitudes. When I stopped to fill up, I got a big rush of air as I opened the gas fill cap. Being a 74, the car has a non-vented gas cap. Besides the big pressure release, the gas in the tank actually appeared to be BOILING! I did a quick google search which told me it was just doing a "heat exchange," and the info I found said that it was no big deal and to just let the vented gas cap do its work. That's great for the person with the vented cap! But what about for me who doesn't have a vented cap? As I've been on this trip, the car has had troubles either when stopping for lunch (not wanting to start right away) or towards the end of the day (not wanting to stay running at idle). I'll be doing more driving over the next few days in similar conditions and just wondering... Is there something I can do short term to improve things? Is there anything long term I should do? Should I investigate a vented cap? Should I release the pressure often? Sorry for the "run-on" "no paragraph" text, but this is how things come out on the iPad...

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

I think your tank should be vented through the charcoal canister, in the engine bay, under the windshield washer reservoir.  There is a vent line that runs from the tank along the frame rail to the engine bay, and that line can get plugged with rust and mung.  Disconnect it on both ends (tank and canister) and blow compressed air through it to make sure it's clear. 

The idea was that vapors from the fuel tank would be stored in the charcoal canister, then at warm engine temps a vacuum line would suck the fuel vapors out of the canister and burn them in the engine.  This (presumably) kept the fumes from stinking up your garage, like old cars used to do, as fuel evaporated slowly in the tank.  Not that we've ever known an old Corvette that stunk a little bit.  :)

|UPDATED|6/25/2013 5:33:07 PM (AZT)|/UPDATED|


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"Let them that don't want none have memories of not gettin' any."
- Brother Dave Gardner

Ed Zachary..the tank is vented thru the charcoal canister. Chances are the metal lines to/from the tank are stopped up, creating the pressure inside the tank. There is a relief valve built into the top of the tank, and it will pop if the internal pressure gets too great. Bad news is, once it pops, it's popped...no fixing it.

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Joel Adams
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