gas smell from vent hose

Discussion in 'Motorbike Technical Discussion' started by stanley.chou, Feb 20, 2006.

  1. stanley.chou

    stanley.chou Guest

    I smelled gas from my bike (cbr 600rr - 05) and took it into the
    dealer for inspection. They confirmed that the gas I smelled is coming
    from my vent hose. The service guy said that it's due to the fuel
    vapors and completely ok. But no matter how much gas is in the tank, I
    smell the gas vapors from the overflow hose. Further, some guey residue
    that smells like gas is building up (it is gas)at the end of the
    overflow hose. Is that normal? i put a flash light to the end of the
    hose, and I actually see the vapors. There are a couple of drops of
    gasoline that dripped from the vent hose too. is there a way to prevent
    so much vapor coming out?? The bike runs fine though and only vents
    stronger gas smells after long rides. Is that normal? bike has a
    little over 1,100 miles.
    stanley.chou, Feb 20, 2006
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  2. stanley.chou

    FB Guest

    Do you have to disconnect this hose from something to see the vapors
    and the gasoline dripping? My GSXR has a vent hose coming from the top
    of the gas tank and that hose just vents straight to the atmosphere.

    Smelling gasoline fumes is normal under certain circumstances, but
    seeing a lot of gasoline dripping out of hoses is not normal.

    Gasoline and water are both liquids. They both have a temperature where
    they bubble
    and boil when heat is applied. They both have a lower temperature at
    which they evaporate. If the temperature drops below the evaporating
    temperature, the fluids condense.

    So you are smelling and seeing gasoline which has evaporated or

    Your machine probably has an evaporative control system. Gasoline in
    the tank evaporates and the fumes are stored in the charcoal canister
    until you start the engine. Then they are sucked through a one-way
    anti-backfire valve into the intake tract of your engine.

    A very small amount of air is normally sucked through the bottom of the
    canister when the engine is running.

    If you over fill the gas tank above the filler neck that sticks down
    into the tank about two inches, you'll get liquid gasoline down in the
    charcoal canister and it may drip out the bottom.

    If you overfill your gas tank and park in the hot sun, the gasoline in
    the tank will expand, and that could cause liquid gasoline to flow into
    the evaporative control system. You would smell a strong odor of
    gasoline evaporating. If you see gasoline dripping underneath the
    canister, you've overfilled the tank and have flooded the canister.

    There is probably a water separator tube going to the gas tank too. The
    water that is separated probably goes through a hose that dumps the
    water onto the road behind the engine.

    All of these parts are included in your warranty. Honda probably has to
    warranty the emissions control system for 50,000 kilometers. The exact
    distance will be right in the front of your owner's manual. If you
    believe that your evaporative emission control system is not working
    right, you have the right to return the vehicle to the Honda dealer for
    warranty repairs.
    FB, Feb 20, 2006
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  3. stanley.chou

    Paul Cassel Guest

    Gas expands and contracts plus is volatile.

    The vent is there for a reason which is to VENT to the outside. That
    means both suck and blow. You smell the blow stages. Many new bikes come
    with charcoal cannisters to adsorb these odors. It's part of life.
    Paul Cassel, Feb 20, 2006
  4. stanley.chou

    stanley.chou Guest

    my bike doesn't have a charcoal cannister.. the bike is in texas.. only
    california bikes have this... so this is still normal?
    stanley.chou, Feb 20, 2006
  5. stanley.chou

    Paul Cassel Guest

    Yes and many non-CA bikes have this as some mfgs don't wish to make two
    versions of their bikes. For example, my non CA KTM has a cannister
    (well, it did).
    Paul Cassel, Feb 20, 2006
  6. stanley.chou

    alan&alon Guest

    are you sure its the tank vent and not a carb overflow/drain hose????
    alan&alon, Feb 23, 2006
  7. stanley.chou

    stanley.chou Guest

    I'm positive.. it's the vent hose.. from what others have told me, the
    vent hose will blow out and suck in air to control the pressure inside
    the tank.. gas vapor will come out.. they said that it's normal. the
    bike is a non-california bike so the charcoal canister is
    non-existance.. thus, i'll be able to smell the gas vapor.. i guess,
    it's not really common, but it's normal.. most of the time, you are
    riding so you won't be able to smell it, but if you have it idling
    after a long ride, you will notice it.. anyways, that's just what i
    gather from posting this on other forums..
    stanley.chou, Feb 24, 2006
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