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need help to plumb a charcoal canister

Discussion in 'Projects, mods, restoration' started by mopar56, Oct 10, 2017.

  1. mopar56

    mopar56 Active Member

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    Ok so my son got back from his road trip and although could not get the cannister from his old Duster that was wrecked because the cannister was cracked in the accident the classic auto wrecker had another Duster that he sold the cannister out of so we now have a three port charcoal cannister according the maps AHBGuru supplied earlier one hose goes to the tank, one to the bowl vent on the carb and one to the carb, ( ported ), I still am unsure of the third hook up to vacuum but apparently it scrubs off vapors stored after shut off, any thoughts?
     
  2. AHBGuru

    AHBGuru Active Member

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  3. mopar56

    mopar56 Active Member

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    I do understand the vacuum map and obviously many of the vacuum lines can be ignored as they simply aren't on the car it is just that I struggle with how the inside of the cannister works, if vapors are pushed up the line from the tank then stored in the cannister until the car is started then vacuum pulls the vapors from the cannister to the carb what stops the vacuum from pulling fuel up the line from the tank when the tank is near full and the vent line pick up is close to the actual fuel level? I just don't want to suck fuel up the line which could cause a dangerous situation and destroy the charcoal filter.
     
  4. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    The vent valve at the tank is closed until a certain pressure threshold is set. That's what keeps fuel from being sucked from the tank into the canister. But if the tank is full on a hot day in the desert, at that point the valve might open to relieve pressure buildup in the tank, and some liquid might travel along with vapor, under the right conditions.
     
  5. mopar56

    mopar56 Active Member

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    Ahha...."the vent valve" what vent valve?, remember the tank we have simply has four vent nipples on it which will go to the manifold I have built, no vent valve, what would that look like, where do I get one?
     
  6. mopar56

    mopar56 Active Member

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    OK I think I found my answer, oddly enough I googled imaged "early seventies fuel tank purge valve" and it took me to an interesting thread on ....wait for it..... ALLPAR, lol called fixing seventies and 1980s fuel evaporation control systems, this explained exactly how the four nipple tank worked, unfortunately, this tank didn't use a charcoal canister but it dose use the manifold I just made, what it did was vent the vapors off into the engine crankcase, I will not do this, I will vent to the charcoal canister we just bought and the vacuum used is the same one to the vacuum advance there for only pulling at high idle when fuel is being consumed at a higher rate and therefor at idle it should not pull fuel up the line, I think this should work, I will let you know, thank you all for your help and suggestions.
     
  7. mopar56

    mopar56 Active Member

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    so it looks like my problem definitely was not just the vent at the tank and carburetor bowl but also the fuel grommet at the filler as after one last drive in the Duster for the winter splashed fuel around the grommet it was leaking a bit around it hence the strong fuel smell, so.....to save a divorce, lol, I had my son remove the fuel tank from the car for the winter, poor the gas in his Dakota and we ordered the proper fuel fill grommet as it seems the other ones listed above are too small a diameter for the Duster, the fuel gauge didnt work any way so we will fix that to and re-install the tank with a new grommet and the updated vent line with addition of the charcoal cannister and hopefully all will be well for spring!
     
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  8. AHBGuru

    AHBGuru Active Member

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    Generally, the fuel cap is the "vent" on cars with emissions controls. Later cars, probably just the M bodies, also had expansion cavities built into the fuel tank. I think you'll be Ok with what you have.
     

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