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Re: charcoal canister Posted by Ari [Email] ![]() ![]() In Reply to: charcoal canister, Christian, Wed, 3 Nov 2004 18:58:01 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The purpose of the charcoal canister is to absorb gas fumes from the tank. Then under certain engine operating conditions, a valve on the top of the canister opens, and the fumes are sucked into the intake and burned. Basically, the canister has three hoses - a fat one to the gas tank; a fat one to the intake plenum, and a thin one to the throttle body that actuates the valve.
Three things can go wrong with the canister - the valve can fail, it can leak, and the charcoal can become contaminated and no longer absorb fumes. If the valve fails open or the canister leaks, you'll get a bad idle, because you'll have a vacuum leak. If the valve fails closed, or the charcoal becomes contaminated, you'll never know it. There will be no effect on engine performance. In fact, more modern cars have special tests as part of the emissions controls to test the charcoal canister operation, because on the older cars, if it doesn't work, you can't tell.
So, what does this mean to you? If you feel that you have a personal stake in preserving the environment, you could replace the canister on the off-chance that the charcoal is contaminated. No way to test it that I now. This would reduce some fuel vapor emissions. However, if you're that much concerned about the environment, get rid of your '87, and buy a newer car with much lower emissions.
If the cansister isn't leaking, and the valve works, then leave it alone. Basically, if the car idles fine, the canister is probably fine, leak-wise. If the car has a poor idle due to a vacuum leak, plug/clamp the two hoses to the canister - if that fixes the probem, then maybe you replace the canister.
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