charcoal canister help
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Intermediate
Joined: Apr 2025
Posts: 34
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From: Canon City, Colorado
charcoal canister help
One of the valves in my charcoal canister (1988 Corvette) has failed some way, and gas fumes are streaming out of the tank around the gas cap once the car is running warm. I cannot buy the whole unit again - at least not a form that looks like what was stock. What is the best solution?
Burning Brakes
Joined: Aug 2008
Posts: 901
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From: Tampa, FL
One of the valves in my charcoal canister (1988 Corvette) has failed some way, and gas fumes are streaming out of the tank around the gas cap once the car is running warm. I cannot buy the whole unit again - at least not a form that looks like what was stock. What is the best solution?
Otherwise, I would also check the vacuum to the cansiter as well to make sure it's actually good.
Melting Slicks
Joined: May 2019
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From: Mid-Atlantic
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Have you inspected the tank itself? There's a couple of places that you really just can't see, even with a flashlight. Particularly the area adjacent to the rear bumper cover.
My tank was rotted and split all the way across, which I only discovered after buying the car when it failed a tank pressure test in the inspection lane. Apparently, the only thing holding fuel in the tank was the bladder. Which itself eventually started to leak. The fumes were really bad and naturally rose upward, giving the illusion that it was coming from the cap.
But, maybe it'll be something simple like a valve.
My tank was rotted and split all the way across, which I only discovered after buying the car when it failed a tank pressure test in the inspection lane. Apparently, the only thing holding fuel in the tank was the bladder. Which itself eventually started to leak. The fumes were really bad and naturally rose upward, giving the illusion that it was coming from the cap.
But, maybe it'll be something simple like a valve.
Last edited by Natty C; May 27, 2026 at 04:30 PM.
Thread Starter
Intermediate
Joined: Apr 2025
Posts: 34
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From: Canon City, Colorado
Thank you for the diagnostic suggestions. I will revisit all of these ideas with my mechanics. All the same, my mechanics and the body shop that removed all of the rear components to repaint the rear bumper/spoiler this week. They inspected the lines, vacuum hose and canister components and function. They looked for other issues and found nothing amiss with the fuel tank. Its that canister unit that requires replacement - so I need the part. Any sources for this part or a substitute that works?
Melting Slicks
Joined: May 2019
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Yeah, they would have seen the place where it rots and splits if tey removed the bumper cover.
So far as the canisters, I don't think you can get em aftermarket.
It'd have to be a used one, so far as I know.
And I imagine any used one is more likely to be someone elses old bad one.
Just to add to what 82-T/A had mentioned, though, maybe also blow out all of the vacuum lines attached to the canister. I've read of those getting clogged up with charcoal granuals.
I've also read where people have cut the bottom of the canister off and replaced the charcoal filter and then did a sort of plastic weld to reattach the two pieces afterward.
Anyway. Good luck with it...
So far as the canisters, I don't think you can get em aftermarket.
It'd have to be a used one, so far as I know.
And I imagine any used one is more likely to be someone elses old bad one.
Just to add to what 82-T/A had mentioned, though, maybe also blow out all of the vacuum lines attached to the canister. I've read of those getting clogged up with charcoal granuals.
I've also read where people have cut the bottom of the canister off and replaced the charcoal filter and then did a sort of plastic weld to reattach the two pieces afterward.
Anyway. Good luck with it...
Burning Brakes
Joined: Aug 2008
Posts: 901
Likes: 227
From: Tampa, FL
Yeah... for some reason, I've never seen charcoal canisters being offered anywhere in the aftermarket for early to late 1980s. You can find them for early 1990s and up all day long though.
They do sell the purge valves: 91 1991 Chevrolet Corvette Vapor Canister Vent Valve - Air Intake - Dorman - PartsGeek (universal) ... but you'll have to learn to do plastic welding. :/
Best bet is to find a good original one. I would call Corvette Generations.
They do sell the purge valves: 91 1991 Chevrolet Corvette Vapor Canister Vent Valve - Air Intake - Dorman - PartsGeek (universal) ... but you'll have to learn to do plastic welding. :/
Best bet is to find a good original one. I would call Corvette Generations.
Burning Brakes
Joined: Jun 2005
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From: Wallingford Vermont
I would suggest doing a thorough inspection of your Evap system. I checked all my lines going back to the tank - no blockage, replaced my rubber hoses, determined the separate vacuum valve was stuck -replaced it, then rebuilt the charcoal canister for good measure -there's Youtube videos on that, cut it open/glue it back together.
Melting Slicks
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Yeah... for some reason, I've never seen charcoal canisters being offered anywhere in the aftermarket for early to late 1980s. You can find them for early 1990s and up all day long though.
They do sell the purge valves: 91 1991 Chevrolet Corvette Vapor Canister Vent Valve - Air Intake - Dorman - PartsGeek (universal) ... but you'll have to learn to do plastic welding. :/
Best bet is to find a good original one. I would call Corvette Generations.
They do sell the purge valves: 91 1991 Chevrolet Corvette Vapor Canister Vent Valve - Air Intake - Dorman - PartsGeek (universal) ... but you'll have to learn to do plastic welding. :/
Best bet is to find a good original one. I would call Corvette Generations.
A lot of times I'll buy a part if I stumble across it on the www, regardless of whether I actually need it or not, if it's a part that I know is or is nearing unobtanium.
Like that NOS incandescent power driver, for instance. I knew I'd need that thing some day, so bought it when I saw it listed, and two years later, sure enough, I needed it and all I had to do was go pull it off the shelf and install it when I noticed that the button lights had went out.
Last edited by Natty C; May 30, 2026 at 09:00 AM.
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Burning Brakes
Joined: Aug 2008
Posts: 901
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From: Tampa, FL
Heck, I had trouble finding one out of a '90, so ended up just leaving well enough alone.
A lot of times I'll buy a part if I stumble across it on the www, regardless of whether I actually need it or not, if it's a part that I know is or is nearing unobtanium.
Like that NOS incandescent power driver, for instance. I knew I'd need that thing some day, so bought it when I saw it listed, and two years later, sure enough, I needed it and all I had to do was go pull it off the shelf and install it when I noticed that the button lights had went out.
A lot of times I'll buy a part if I stumble across it on the www, regardless of whether I actually need it or not, if it's a part that I know is or is nearing unobtanium.
Like that NOS incandescent power driver, for instance. I knew I'd need that thing some day, so bought it when I saw it listed, and two years later, sure enough, I needed it and all I had to do was go pull it off the shelf and install it when I noticed that the button lights had went out.
The reality is... someone COULD use that stuff.
I have a rental in South Florida that I haven't lived in, in over a decade. The attic is filled with ultra-rare 3rd gen parts, which I never viewed as rare, including a factory fiberglass cowl hood, and like three sets of cowl induction systems for 82-84 F-bodies. A couple of shaker assemblies, some unobtanium Holley TBI units... none of which I'll ever use, but at the time I thought I would. It sounds hoardery, but it really isn't as bad as I'm making it seem. But all that's been sitting in the attic of a rental. If I eventually move back, I'll probably just give all that stuff away.
Melting Slicks
Joined: May 2019
Posts: 3,243
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From: Mid-Atlantic
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Oh man... you should see my attic. A bunch of stuff I'll never use, but I'm convinced I will.
The reality is... someone COULD use that stuff.
I have a rental in South Florida that I haven't lived in, in over a decade. The attic is filled with ultra-rare 3rd gen parts, which I never viewed as rare, including a factory fiberglass cowl hood, and like three sets of cowl induction systems for 82-84 F-bodies. A couple of shaker assemblies, some unobtanium Holley TBI units... none of which I'll ever use, but at the time I thought I would. It sounds hoardery, but it really isn't as bad as I'm making it seem. But all that's been sitting in the attic of a rental. If I eventually move back, I'll probably just give all that stuff away.
The reality is... someone COULD use that stuff.
I have a rental in South Florida that I haven't lived in, in over a decade. The attic is filled with ultra-rare 3rd gen parts, which I never viewed as rare, including a factory fiberglass cowl hood, and like three sets of cowl induction systems for 82-84 F-bodies. A couple of shaker assemblies, some unobtanium Holley TBI units... none of which I'll ever use, but at the time I thought I would. It sounds hoardery, but it really isn't as bad as I'm making it seem. But all that's been sitting in the attic of a rental. If I eventually move back, I'll probably just give all that stuff away.
Last edited by Natty C; May 30, 2026 at 05:51 PM.
Thread Starter
Intermediate
Joined: Apr 2025
Posts: 34
Likes: 4
From: Canon City, Colorado
Great suggestions all - thank you! I'll get back with everyone on what happens next, and I'm checking on that valve [[url]https://www.partsgeek.com/catalog/1991/chevrolet/corvette/air_intake/vapor_canister_vent_valve.html] to see if it's the fix. I hope so.
One other note...I did change the gas cap at the suggestion of the mechanic. With the car cold (not run for days) at about 70 degrees, the vapor pressure in the tank was high as fumes rushed out with the cap removal. Its not a cap issue.
One other note...I did change the gas cap at the suggestion of the mechanic. With the car cold (not run for days) at about 70 degrees, the vapor pressure in the tank was high as fumes rushed out with the cap removal. Its not a cap issue.
Last edited by drbutton; Jun 1, 2026 at 03:47 PM.
Intermediate
Joined: Jan 2026
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I recently ran into a fuel pressure issue myself. I posted this thread here a couple months back. I got some good suggestions, and schematics too from others here. I cut the charcoal canister open, refilled it and put it back together, a purge valve, and a couple other things. It worked for me. I don't have any issues now.