evaporative control canister
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
evaporative control canister
any issues with just disconnecting the vacuum line from the evaporative control canister to the carb. i did and the car seems to run and idle better. any reason i can't just disconnect this system? also, there seems to be two vacuum lines from the canister. one small diameter like the headlight hose and one larger diameter like the PCV hose. why two?
Instructor
Joined: Apr 2006
Posts: 105
Likes: 0
From: Knoxville TN
I disconnected mine a while back and asked the same question and everyone said it was ok. I do believe someone said to put a vented gas cap on since capping it will build up negative pressure but Ive noticed no issues but I dont think Ive put gas in since then.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
One line goes to the tank vent, the other goes to the vacuum system and opens the valve on the canister to return the vapor into the system to be burned. The 3/8 line goes to the floatbowl vent on the carb.
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
I ordered a vented gas cap last week, can't wait to plug that piece a' crap cannister up, hope it will get rid of the gas smell in the garage. I think it's pretty much plugged up as it is, I get a lot of pressure in my gas tank after a short drive; open the tank and the cap practically jumps a foot! Scarry.............
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
well, gosh then i have another question. my 79 L82 didn't have a screw on gas cap when i got it. it's always had a "quick fill" cap. spring loaded opening in the middle of a cap that doesn't appear to screw off. you just insert the fuel nozzle in the little spring loaded area. was this stock? or and aftermarket mod? hope someone can answer this. since it's not air tight i assume its considered a vented cap. thanks for any info.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
The right thing to is to fix the canister. It should not be a vac leak. Fix it and hug a tree all at the same time. Thats one system that does not suck up horsepower. You will probably find that the fume problem gets worse, since the canisters job is to contain them.
Le Mans Master
Joined: Jan 2007
Posts: 7,948
Likes: 3,315
From: Omaha NE
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
2022 C3 of the Year Finalist - Unmodified
2020 C3 of the Year Finalist - Unmodified
well, gosh then i have another question. my 79 L82 didn't have a screw on gas cap when i got it. it's always had a "quick fill" cap. spring loaded opening in the middle of a cap that doesn't appear to screw off. you just insert the fuel nozzle in the little spring loaded area. was this stock? or and aftermarket mod? hope someone can answer this. since it's not air tight i assume its considered a vented cap. thanks for any info.
Drifting
Joined: Nov 2005
Posts: 1,795
Likes: 1
sixfooter,
i dont want to hijack this thread but this is basically what i asked
a couple of days ago in my edelbrock post.
my dilemma is the edlebrock has no provisions for the 3/8s
line that was on my original Q-jet and i was asking where this line
should go.
i have the PCV hooked up and the vacuum line connected and the 3/8 plugged for now, i dont want to remove the system because once lars is back doing carbs again im going to have him rebuild my original Q-jet
and reinstall it and hook everything back to stock.
any ideas other than plugging as others have done is appreciated.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
well, with all the other emission stuff already removed by previous owner, cat, smog pump, EGR, etc. hard for me to believe disconnecting the cannister on my 79 is going to send the global warming situation over the tipping point, especially with 2 billion chinamen building a new coal plant ever 3 days and putting 10,000 new vehicles a day (yup) on the roads of China. just my 02.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
sixfooter,
i dont want to hijack this thread but this is basically what i asked
a couple of days ago in my edelbrock post.
my dilemma is the edlebrock has no provisions for the 3/8s
line that was on my original Q-jet and i was asking where this line
should go.
i have the PCV hooked up and the vacuum line connected and the 3/8 plugged for now, i dont want to remove the system because once lars is back doing carbs again im going to have him rebuild my original Q-jet
and reinstall it and hook everything back to stock.
any ideas other than plugging as others have done is appreciated.
i dont want to hijack this thread but this is basically what i asked
a couple of days ago in my edelbrock post.
my dilemma is the edlebrock has no provisions for the 3/8s
line that was on my original Q-jet and i was asking where this line
should go.
i have the PCV hooked up and the vacuum line connected and the 3/8 plugged for now, i dont want to remove the system because once lars is back doing carbs again im going to have him rebuild my original Q-jet
and reinstall it and hook everything back to stock.
any ideas other than plugging as others have done is appreciated.
My 81 has like 6 lines on it I think. Tank, Carb Bowl, PCV, Breather, vac lines for purge, vac control from TVS
Here is the diagram
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
well, with all the other emission stuff already removed by previous owner, cat, smog pump, EGR, etc. hard for me to believe disconnecting the cannister on my 79 is going to send the global warming situation over the tipping point, especially with 2 billion chinamen building a new coal plant ever 3 days and putting 10,000 new vehicles a day (yup) on the roads of China. just my 02.
Race Director
Joined: Jul 2004
Posts: 12,696
Likes: 329
From: Scottsdale Arizona
There are a couple of indents in the bottom of the canister. They are the same size as 3/8 inch dowels. I know that they are supposed to unscrew but I have never been able to make mine work. In the end, i gave up and bought a new canister. I have a lovely, never used replacement filter pad for sale if you're interested.
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
Resurrecting Vapor Canister thread
any issues with just disconnecting the vacuum line from the evaporative control canister to the carb. i did and the car seems to run and idle better. any reason i can't just disconnect this system? also, there seems to be two vacuum lines from the canister. one small diameter like the headlight hose and one larger diameter like the PCV hose. why two?
On the subject of disconnecting this canister, my only question is what to do with the hose that goes to the PCV valve and then tee's off to the carb, should I just plug it between the PCV valve and the canister? I am ready to go drive this for a while and see if the gas stink persists in the garage. Mine is a '72 with 350............Thanks
Race Director
Joined: Apr 2003
Posts: 19,348
Likes: 654
From: Tampa, Florida
My system is all messed up and disconnected. I plan on fixing it but until then I'm going to install a vented gas cap to see if my time bomb garage will disable itself.
Last edited by jim2527; Mar 16, 2007 at 06:57 PM.
Melting Slicks
Joined: Sep 2006
Posts: 2,810
Likes: 469
From: Wichita Kansas
Well, I'll tell ya ..................
Nothing has changed here; I removed the stupid canister, plugged the line from the fuel tank, plugged the two lines from the [former] canister, put a vented gas cap on, still smells of gas. I am going to remove the spare tire and try to feel if the fuel separator valve is still snug in place on the drivers side top of the gas tank; if I can reach it, I will order a replacement just to be sure. If this does not work, I will buy some hose and hook the canister back up and run this hose back to the tank (this will test weather the original vapor line is plugged or not). If that doesn't work I will park the car on a railroad track because that's about as fed up with this crap as I am.....................In the meantime, will leave the garage door cracked open.
