[aeilenstein]

My '77 has an evaporation canister up on the driver's front of the inner fender. I noticed that the evap canister is very loud at idle. I mean it sounds like alot of vacuum is running through it. How important is it to keep this? I don't know that it's hurting anything, just wanted to know some opinions on it. I suppose I don't really understand its purpose! Thanks.

 

[f3nderbass]

The evaperation canister is part of the emissions system on your cruck, or any car to be exact. There are two hoses going to your canister. One hose goes to the gas tank, the other to the engine. The one going to the gas tank recieves fuel vapors from the tank, this keeps fuel vapors out of our atmosphere. All these vapors come into the canister and the canister "soakes" them up like a sponge. Then the line to the engine takes those vapors and uses them as fuel and burns them.

So the job of the canister is to trap vapors and burn them, making sure no gas goes to waste nor into the atmosphere

Now your canister sounds like it may be cracked, or have a leak, thus causing the vacuum from the engine to pull air from outside the canister, rather than pull vapors from inside. It may be time to replace it, but check to make sure its the canister thats broken, rather than a simple vapor line.

Reasons why you should make sure to have a working vapor canister:

Keeps our earth clean, them EPA guys aint all that bad
You will have a strong fuel smell without it
You would have to switch to a different fuel sending unit without a vapor line exit
The unburnt fumes may ignite somewhere in your car, instead of be trapped

 

[Lenny Carey]

Adam , the explanation f3nderbass gave is excellent . Do a search here on ECC as this has been discussed with some good advise . Some will tell you to eliminate the charcoal canister but I think it is best to keep it for the above described reasons . If it is not cracked , it may be that it is plugged with slime as the bottom of the canister is open . One of our members has described a clever and cheap fix using fish tank filter materials . New ones are readily available at auto parts stores or if cracked , you can get one out of a salvage yard and refill it with the filter material .

 

[Jack_K]

Reasons why you should make sure to have a working vapor canister:

Keeps our earth clean, them EPA guys aint all that bad
You will have a strong fuel smell without it
You would have to switch to a different fuel sending unit without a vapor line exit
The unburnt fumes may ignite somewhere in your car, instead of be trapped

I agree with the first reason, but I dispute the other reasons.

I have no canister connected in my '80 and I have no gas smell at all.

I have the original sending unit.

If no smell, probably no fumes. If no fumes, probably no fire.

Of course, this is based solely on MY car.

I am NOT advocating removing the canister. I just haven't reinstalled mine since cleaning and painting the engine bay.

Jack

 

[aeilenstein]

Thanks for the great information. Sorry I didn't do a search first before I asked. My canister is only about 9-10 months old and only has 3-4 months actual engine run time on it, so I would hope it's not cracked--will check it out at home this evening.

Is the evap (vapor) canister supposed to be hooked to manifold vacuum or a ported vacuum source? Mine is currently hooked to vacuum tree on back of intake manifold. Thanks.

 

[aeilenstein]

Oh, could this be my mystery vacuum leak I've been chasing for a few weeks if it is cracked?

 

[mrblanche]

First of all, that canister should not be hooked up to a strong vacuum source like the manifold. Depending on what carb you have, it needs to be moved from where you have it. Otherwise it will act like a large vacuum leak.

 

[dills88]

check you vac map under your hood that vac line go in front side of your carb on useally top of fuel bowl on most carbs from the factory

 

[aeilenstein]

Unfortunately, after 35 years and who knows how many owners, the vacuum stickers are long gone. I also don't have the Quadrajet carb anymore, but can fab up an adapter to run the 1/4" hose from the canister down to 3/16" line for the ported vacuum port on my carb. If that is still too strong a vacuum signal, then what are my options? On my carb/engine, my ported vac opens at 850-900rpm. Thanks....

....learning now about critical nature of vacuum routing and modification.........:???:

 

[gwgdog66]

I had a knock out on the bottom of my aftermarket air filter. I ran a 45 rubber PVC grommet to it (for a chrysler) and used a plastic inline vac hose adapter to a hose to the canister. It works great and no smell.

Unfortunately, after 35 years and who knows how many owners, the vacuum stickers are long gone. I also don't have the Quadrajet carb anymore, but can fab up an adapter to run the 1/4" hose from the canister down to 3/16" line for the ported vacuum port on my carb. If that is still too strong a vacuum signal, then what are my options? On my carb/engine, my ported vac opens at 850-900rpm. Thanks....

....learning now about critical nature of vacuum routing and modification.........:???:

 

[80v6]

Vapor cannister.

Some years have a filter on the bottom like an air filter. Also, I read an article a while back about the filter media inside the cannister is not the same as the aquarium media. Aquarium media is designed to filter water not vapor. You decide.

 

[neller840]

My theory is why waste the fumes?? Just don't see why not... Your not taking away HP, however it does add to all the hoses running to the engine. Done right it can look clean, and your repurposing fumes that would otherwise just float off wherever.

I like the idea of running the canister to the air cleaner. Mine has three hoses, it also has a "purge" on it as well. Believe it once went to the smog setup that was ripped off long ago. I was thinking of just putting a T adapter with elbows to both output connections, and run one hose to the air cleaner. Anyone have any input. I'm guessing they are both outputs from the charcoal canister, and both could be fed back the engine. :dontknow:

 

[steelybill]

The question was about the importance of the canister, and GM wouldn't spend an extra dime if it wasn't required for emmision standards. Removing it doesn't help the engine any, just adds pollution to the atmosphere we breath.

 

[steelybill]

I just looked in my "77 service manual, and it has vacuum diagrams in it. I can copy those and probably post them here, if anyone is interested. Some changes would be necessary, since the '77 year used a 2bbl carb etc
Bill

 

[ccc]

on a late 70 s car it should go to the bowl vent on the carb air horn. it should also be hooked to the fuel vent line from the tank. some will have a valve hooked to the pcv valve to triger the canister to purge when the engine startes.without a pic of your particular set up it is very hard to tell what you have/need. i have seen car fires caused by a bad or disconnected canister. so you want it right and not bypassed as it is the venting system for the fuel tank as its primary function and emissions as its secondary .

 

[1983SS454]

I agree with the first reason, but I dispute the other reasons.

I have no canister connected in my '80 and I have no gas smell at all.

I have the original sending unit.

If no smell, probably no fumes. If no fumes, probably no fire.

Of course, this is based solely on MY car.

I am NOT advocating removing the canister. I just haven't reinstalled mine since cleaning and painting the engine bay.

Jack

Same here, no issues. No problems, haven't had it on there In years

 

[Bryan59EC]

Hmmm
Both cannisters in my 79 C-10 were connected to the same line as the PCV.
Still are to this day.
Bought the truck new and that is how it was routed on the wheezy 305.
I routed them the same on the 350 and later the 454 that went into the truck

 

[oldtinsmith]

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?chapterTitle=Vacuum+Diagrams&partName=Emission+Controls&pageId=0900c1528005163f&partId=0900c1528005154c

Hope this works!

Doug