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Charcoal Cannister ??

badmix

badmix

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I have one line coming to it. Is there a way to eliminate this thing? put some kinda filter on the end of the house> Im guessing its from the rear of the tank, considering its a rubber hose that is 8-10" long and then goes into a metal fuel line.

What are your solutions?
 
My metal tube goes to my front diff. Well, to the rubber hose that goes to my diff. And one hose that goes to my TBI. I was just going to run a small filter for my diff and block off the TBI hole and remove the charcoal canister.
 
badmix said:
What are your solutions?
Click to expand...

Run the outlet from it to the carb/throttle body?

I beat myself trying to come up with better tank venting options for a long time, IMO there is really no better solution than what GM came up with. No fuel vapors being vented that could combust, pretty good barrier to airflow into the tank, keeps bugs, mud and water out, etc.

It's so simple (line in, line out, solenoid/switch in most cases AFAIK) I don't see anything else working as good.

After all that, I'm running a cap that I made vented, with a bolt in the EVAP line, since I put this thing together before I knew better, and I'm just not going to take the time to put it back on this truck...but it will come over with the body when I swap from the new truck.
 
Unless I missed it, I only have 1 line at the cannister, all the others are plugged.
 
It totally changed with TBI, not sure what year you have?

I got rid of mine (1983) and am just venting the tank through that line. I think I put a little filter or something, I'll have to go check. It's not hurting anything, but it did open up some space, which is nice.

Interesting point about fuel vapor. Seems unlikely to be a problem, but I guess it's something to consider. Engine bay is pretty drafty.
 
What year are you dealing with? The TBI ones had only two lines, in and out, the earlier carbed ones (perhaps HD was different) tended to have a few more fittings.

Having a hard time finding a repository of the various GM Evap canisters as there were quite a few variations. I don't think GM used plugs.

I'm curious now if the vacuum source for Evap, when "active" was full manifold, or if it was somehow reduced/timed. On my car (again before I knew better) I just hooked the Evap outlet to the carb with no valve, but that is basically a vacuum leak. With the later non-vented gas caps, you'd think that would cause other issues as well.
 
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I believe there is a high altitude emissions one and has another hose line or two. Mine had a little more stuff on it. Looks like I have 3 hoses instead of 2.

canister1.jpg

canister2.jpg
 
Probably looks something like the first one jeff in co posted then I assume?

Based on the one in that picture, the little fitting would be vacuum to "open" one of the large fittings/lines to the carb, and the other large fittingswould be the line to the tank.

If you could easily tee the two carb side lines together it would be simple to test and see if it hurt driveability, but since they are different size hoses, not going to be done easily. Guaranteed GM had the "signal" vacuum line run through a TVS or other switched source to keep it closed during certain times of engine operation originally. It's why the carbed engine bays were such a mess of vacuum lines.
 
Ill have to look, but I dont have any lines going from charcoal to carb. ONly the PCV from carb to valve cover
 
I won't state with authority that's not right, but really no point in running evap if it didn't go to the carb. Everything I've ever seen has been that way.
 
Well, I am running a Holley 570 street avenger on there right now, I know I got rid of alot of lines. Ill look again but Im 99.9999% certain, I dont have anything lines going from charcoal to carb. Just the one line that is metal and then goes to rubber into the charcoal cannister. Its to the very LEFT of the cannister if your standing at the front of the truck, looking down into engine bay.
 
You may not have them now, but that's the only way to run it. If it's got the valve on top, you'd have to run another line to open the valve so it would purge when the truck was running.

Metal line to rubber should be the line from the tank. Everything else to the EVAP cannister is rubber that I've seen.
 
Ok. so essentially, i need to run a vacuum line to the cannister to make it work. Ive had it the way it is for 5-6 years or more. Any danger to leaving it alone or pulling the cannister and just putting small filter on the gas tent vent? or it doesnt work that way.
 
Well if it has a valve at the top of the cannister (so three open fittings) you'd have to use the fitting on the valve to open it, so one vacuum line, then another line hooked to the carb to "ingest" the fuel vapor from the remaining EVAP fitting.

Likelihood of any issue by venting the tank as you describe? Pretty low I'd say. *Possible* you could ignite gasoline vapors that way? Yes.
 
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