• VAPOR CANISTER - FUEL LEAK
  • VAPOR CANISTER - FUEL LEAK
  • VAPOR CANISTER - FUEL LEAK
  • VAPOR CANISTER - FUEL LEAK

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  1. #1
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    Default VAPOR CANISTER - FUEL LEAK

    Have an 81.
    Still learning my way around the car, just got it in the fall and have very little experience.
    Spring has come and I had the car out a few times, yesterday being the longest time this year, approx an hour driving or so. (Note: I had taken it on several 2 hour trips in the fall, and this problem did not occur)
    When I returned home I had the car idling in the driveway, when a fuel leak apparently started, and ended relative shortly. It was a bit dark, but I pinpointed the general area of the leak (behind the front driver wheel). I turned the car off and grabbed a pan. I would guess that about 12-16 ounces leaked. It stopped dripping after a few minutes.
    With better ligthing this morning, I found that the fuel leak came from the vapor canister. On the bottom of the cannister is an outlet, but there is currently no hose connected to it. I cannot find any disconnected hose nearby. It it apparent that the fuel came from this outlet at the bottom of the cannister, as there were still a couple drops of fuel around the area this morning.
    Would there be any reason for the previous owner to simply disconnect or remove the hose that connects to the bottom of the canister????
    Looking in the shop manual, it appears that the outlet should be for a return line to the tank.
    Any advice anyone can provide would be much appreciated.
    Thanks,
    Al

  2. #2
    Member duke94's Avatar
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    The hose that is on the bottom of the canister is just a drain. There should NOT be any gas in the canister, just vapors from the tank. There is a fuel separator on the side of the tank (speaking of my 78' and 71' ) with a check valve in it to stop any liquid fuel from going down the evap line. Your's does not appear to be working. This is a photo of the separator on my 71'

    Gary


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    Thanks for the reply.
    I have some comments and questions.
    The separator is near the top of the tank. I have not had the tank past half full for perhaps the last 5 months. When this leak specifically occured, it happened after an hour of driving with the tank between 3/8 and 1/8 full. Would seem unlikely that the fuel level would recently sway up to the point where the separator is located. Could it have been fuel from 5 months ago when I last had the tank nearly full?
    What is the function of that drain on the bottom of the canister?
    Another point I would like to reiterate is that the leak was a sudden occurence. Like something ruptured. Even if there was liquid fuel inside the canister for a long time, why would it suddenly pour out?
    Any comments or advice from anyone would be much appreciated.
    Thanks,
    Al

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    Member duke94's Avatar
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    Here's the trouble shooting info from the GM manual. Note that there are a couple of things that can cause raw gas to get to the canister. Hope it helps.

    Gary




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    Gary,
    Thanks for the reply. I actually have the shop manual, but to a total layman like myself, it's like reading Latin.
    Ultimately, I would get any repair done by a local shop, but I don't have a long history with the shop, so I like to have an idea of what the issue is beforehand.
    So, I was hoping that perhaps someone saw the exact same thing happen in the past.
    To recap the issue....
    A sudden purge of maybe 12 ounces of liquid gasoline from the vapor canister or perhaps a hose connection above it. Took about 3-4 minutes for the 12 ounces to drip out. This was done after about an hour of driving in 80 degree weather with roughly 1/4 tank of gas. The gas cap had not been removed for 5 months.
    If someone has a theory, let me know.
    Regards,
    Allen

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    Member 73shark's Avatar
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    I'm betting that it's the vacuum operated purge control valve if all of the hoses are hooked up correctly.
    Save the wave

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