Charcoal canister

[mjoekingz28]

I think this is what takes engine vapors and vents them cleanly to atmosphere. Does this part need any maintenance, monitoring, or changing from time to time?


I don't know if they clog or maybe the (activated carbon?) loses its effectiveness.

 

[Bandito440]

Its purpose is to prevent unburned hydrocarbons (fuel vapors) from being released into the atmosphere. They're eventually burned in the engine.

If you get a check engine light and corresponding evap code, it may need to be replaced. Aside from that, leave it be.

 

[Rolla07]

Your check engine light will illuminate. Ironically mine just came on P0456 is the code...going to replace the gas cap and hope its all it was..apparently dealer charges 1000$ here to replace the charcoal canister...if it happens to be the canister..this car will just keep trucking on without changing it.

 

[Kruse]

These can allegedly be damaged by filling your gas tank to the absolute top or continually adding gas after the nozzle has clicked. Yes, some makes and model have higher failure rates than others.
What make and model? What symptoms do you have that you think it may need to be replaced?

 

[SteveSRT8]

The purge valve is the key, it controls the canister which is never vented to the atmosphere, only to the intake manifold. If the purge valve becomes cranky there may or may not be a code but you could smell the gas fumes backing up in the canister...

 

[Kira]

Correct, the canister absorbs fuel vapors, the purge valve opens and fresh air and vapors get sucked into the engine.
This clears the canister.
On my sister's '99 Cherokee the purge valve was on the firewall and you could hear it "sniffing" rhythmically whenever the engine was on.
Upon shutdown all cycling of it opening and closing ceases.
It's in the closed position. The charcoal is clean and can absorb.

I believe overfilling my '02 volvo caused 2 weeks of EVAP related codes until the canister dried out.
I kept the tank no fuller than half-way during that period.

Now I play number games with the dollar amount at click-off. I call it "What cents does this make?"

 

[Eddie]

I always play safe and never top up my fuel tank after the first or second click off. Ed

 

[JC1]

Originally Posted By: Eddie
I always play safe and never top up my fuel tank after the first or second click off. Ed


+1, I do the same thing.

 

[Errtt]

On one of my vehicles years ago I found the vapor canister filter caked up with dirt (dried mud) I guess from 4-wheeling off road. Til then I didn't know it had that filter at the bottom of it. Changing the filter was all I did to it.

 

[Letsrunum]

I've been doing some research into this myself for my 1970 cutlass Supreme project. My 1972 had one on it. But, it was missing on my 1970 Cutlass Supreme. I found this diagram to see what all it went too.

The original key lock gas cap is not a vented cap. Does the charcoal canister let the gas tank vent? Trying to see what all I can eliminate as well
From a V8 403


I bought the filter from summit that goes on the bottom

 

[mk378]

Right, the gas cap is not vented. If pressure builds up in the tank, it is relieved through the canister, with the HC vapors adsorbed out before they can pollute the atmosphere. While driving, as the gas is used up, air will enter the tank through the canister. This all happens via the "To Fuel Tank" hose.

The gas cap should have a pressure - vacuum relief valve to protect the tank from damage by abnormal pressure if the evap system does not work as intended.

 

[Letsrunum]

On my 72, someone cut the line on the canister that was going to the carb. That made it vent into the engine compartment right?

I thought about putting a filter inside the hose by the gas tank, so it could vent and keep things out of the gas tank. But, it would also require maintenance from time to time under the car. If the filter was to ever clog, the pressure/vacuum relief valve would open up.

This was to eliminate the canister

 

[Letsrunum]

The other thought was to put on a vented cap and plug the line off by the tank. Find one that uses a key, to keep people from putting something into my gas tank.

 

[circuitsmith]

You should have at least a pressure relief on the tank, not just an unrestricted vent.
If the tank can't build some pressure at rest the lighter fractions in the gas will evaporate and make it stale.

 

[Lyman]

The only problem I have ever had was when I had the hose that goes from the top of the gas tank to the canister come off.
I had a steady CEL. It was on a 99 Ford Ranger. I ended up pulling the bed off to find it. It's the only way I could see it.

 

[Leo99]

After 300k miles of filling up the gas tank to the next round dollar amount, my wife's Rav4 took two tries to start after she filled her Rav up with gas. Either the charcoal was saturated or the purge valve had rusted. I changed out some easy to access valve under the hood put that had no effect. Since the purge valve on the Rav is integral to the charcoal canister, I changed out the whole thing and that fixed the problem. Canisters are expensive. Dealers want about $350 for one for my Rav at the parts counter and I was lucky enough to find a local dealer selling one on ebay for $220.

I would just leave it alone if I were you. They should last a long time and on the Rav, there is a tricky gas line clamp that is difficult to get off without breaking.

 

[01rangerxl]

The EVAP system is supposed to be maintenance free, but they can become damaged, or there may be a design issue that requires attention.

On some GM full size trucks, the vent valve assembly can get clogged with dirt/mud and there are revised parts/installation procedures that relocate the vent valve and its plumbing. There's a bulletin that addresses it. The charcoal canister itself is rarely a problem unless it gets physically damaged or flooded with fuel.

I have heard of some vehicles being sensitive to overfilling. On vehicles with EVAP systems, it's never a good idea to try filling past when the pump clicks off.

 

[bunnspecial]

It's routine on MGs to "regenerate" the cans by opening them and dumping out the charcoal, lighting it on fire, and letting it burn out. You then put it back together with fresh top and bottom foam.

The purpose of lighting it on fire is to burn off any gasoline that's hanging around after 40+ years. Obviously it's done in a safe place well away from the car or anything else flammable. For the less adventurous, you can refill with course aquarium charcoal.

BTW, on MGs(with the exception of the very last models) you have a single can located where the pedal box would be on a right hand drive car. They have three connections-one from the gas tank top to scavenge vapors(used with an unvented cap), one from the carb overflow vents, and one to supply make-up air to the crank case.

It's nice, though, to look back to a time when you have a part performing basically the same function in the same way as on modern cars, but that can be fixed so easily.

 

[Letsrunum]

One of many

http://www.google.com/patents/US5327934

 

[Letsrunum]

I have two lines on mine