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  1. #1

    Default Charcoal Canister Hookup

    Hey guys,

    I'm back begging at the altar of knowledge with nothing in return....
    I'm 99% certain I've pinpointed the cause of the rough idle/intermittent stalling in my 1984 5.0, and it's a lack of charcoal canister. Over the weekend when trying to replace the broken hoses coming from a purge solenoid I couldn't find one of the hookups, that's because the canister must have come loose and fallen off.

    So my question is this: is it just as simple as installing a new canister and hooking it up to the carburetor through the solenoid, or does this one need to be hooked up to the gas tank as well? As far as I understand, there's 2 of these, 1 in the front fender, the other mounted on the frame rail below the battery. I'm missing the one mounted under the battery.

    Here's where it should be:
    Name:  charcoal_canister_location_highlighted.jpg
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    And this is a diagram of a 1985 engine I found, it's from another thread but I've circled which canister I'm missing. It's similar enough to the 1984 to show what I mean:
    Name:  charcoal_cannister_diagram.jpg
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    Cheers guys!
    Last edited by Moister Oyster; 03-06-2018 at 09:11 PM.

  2. #2


    Why do you think that the lack of a charcoal canister is causing rough idle?
    Unless you have to pass a detailed smog test, just let the bowl vent to the atmosphere.

    Before pollution was a concern, the bowls just vented into the atmosphere.
    But, with a ~100 million cars, and hot places like Southern Cal, that ends up being a lot of evaporated gasoline into the atmosphere.

    So, they mandated that the evaporated gasoline be captured, then returned to the gas tank. Well, in theory. A lot of the gas fumes get absorbed by the charcoal, and stay in the charcoal. Yea, some gas fumes do make it back into the tank.

    If you hook up a charcoal canister, then the purge valve must also be hooked up and functioning.
    Or, vent the purge side of the charcoal canister to the atmosphere - note that would not pass a detailed smog inspection.

    Fwiw, I changed my charcoal canister about 7 years ago. I figured that the original was useless. I still needed to pass smog. Plus, it doesn't hurt gas mileage, nor performance. And, it does help (very very little) with reducing pollution.
    Last edited by stangPlus2Birds; 03-06-2018 at 09:26 PM.

  3. #3


    Plug the vacuum line, see if the rough idle goes away.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  4. #4


    I had an issue with surging idle and extremely bad gas smell when driving my 86 5.0 capri. I replaced the charcoal canister and the solenoid and both the surging idle and vapor smell problems went away.

    I think the canister was clogged or the solenoid was bad so the vapors weren't getting routed back to the tank and were just vented into the engine bay and therefore pushed back into the passenger compartment. It was bad enough that I started carrying a fire extinguisher.

    However, I don't know why that would have fixed the surge at idle?! I bought an idle air control adjuster from one of the big box Mustang shops and haven't installed it, yet. I thought that the surge would have been a vacuum issue, but all research pointed to the IAC..

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