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Thread: Boiling gasoline in gas tank

  1. #1
    Join Date
    Dec 2018
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    10

    Default Boiling gasoline in gas tank

    Has anyone ever experienced boiling gasoline in the gas tank? I whet for a 10 mile ride in the afternoon and the temperature was about 100 degrees. I parked the bike in the garage and went inside for a few minutes. When I returned to the garage I heard a hissing noise and discovered it was the gas tank on the bike. I removed the gas cap and it release the pressure which stopped the hissing noise. I looked in to the gas tank and noticed the gasoline was boiling inside the tank. The gas tank was close to empty at the time as I was trying to see how far I could get on a tank of gas. I was at about 50 miles when this happened.

  2. #2
    Join Date
    Nov 2008
    Location
    Virginia
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    489

    Default

    Sounds like your cap vents are blocked and not allowing vapors to bleed off.

    Tom (Rollo) Hardy
    AMCA #12766

  3. #3
    Join Date
    Oct 2011
    Posts
    479

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    Happened on my 34.Sounded like tea kettle.less likely with more gas in the tank.
    Tom

  4. #4
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,276

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    Rollo's nailed it, 1932VL!

    The "flashing" when the pressure is released is like popping open your favorite carbonated beverage.

    .....Cotten
    Last edited by T. Cotten; 10-11-2019 at 04:45 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #5
    Join Date
    Jan 2006
    Location
    Menomonie, WI
    Posts
    1,262

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    1987 on the way to Sturgis we stopped in Sioux Falls for gas and to cool off and when I finally got my bike (47 Knuckle) to quit dieseling I could hear the gas burping in the tanks. Sign on the bank said it was 114 degrees. Years later when I took the tanks off the paint was blistered underneath and I think it probably happened that day. Unbelievably hot.

    Jerry


    Quote Originally Posted by 1932VL View Post
    Has anyone ever experienced boiling gasoline in the gas tank? I whet for a 10 mile ride in the afternoon and the temperature was about 100 degrees. I parked the bike in the garage and went inside for a few minutes. When I returned to the garage I heard a hissing noise and discovered it was the gas tank on the bike. I removed the gas cap and it release the pressure which stopped the hissing noise. I looked in to the gas tank and noticed the gasoline was boiling inside the tank. The gas tank was close to empty at the time as I was trying to see how far I could get on a tank of gas. I was at about 50 miles when this happened.
    Last edited by Jerry Wieland; 10-12-2019 at 10:47 AM.

  6. #6

    Default

    This past summer I had my '25 JD out for a run on a hot day and then had it idling in the driveway for a bit while I adjusted the carb. A few minutes after I shut it off I heard the sound of liquid spattering on the hot exhaust. I looked over and saw a little fountain about 2 inches high spurting out through the gas cap vent. It turned out that I had filled the tank a little too full and the gas had expanded above the hot engine. Needless to say, I moved pretty fast to drain off a little and prevent a bigger problem.

    Next time I fill the tank I'll have to go for a longer ride.

    Peter

  7. #7
    Join Date
    Jan 2003
    Location
    England
    Posts
    1,312

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    The VLs do run hotter than the later bikes, and you need to be careful to watch out for low fuel levels on a hot day, overfilled tank and clear tank cap vents. In 1932 the left tank fuel line runs really close the to the rear cylinder, remedied in 1934 when a slanted tank outlet became standard and the fuel line was re-routed outside the shifter mechanism.

  8. #8
    Join Date
    Dec 2018
    Posts
    10

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    Thank you all for the wealth of information on this matter. I have replaced the gas cap with a new one and found the old gas cap was obstructed (Rollo). I am in the process of cleaning the old gas cap. I will use the new gas cap, ride in cooler weather, and keep the gasoline levels closer to full to prevent any further issues. The paint around the gas cap blistered due to a bad paint job. I took her out last week and she did fine, no issues. Again thank you all, it's nice to know there are others with similar issues when it comes to these old bikes, but more important those with the knowledge to guide us.

  9. #9
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,276

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    Quote Originally Posted by 1932VL View Post
    ...The paint around the gas cap blistered due to a bad paint job....
    Lots of perfect paint jobs, 1932VL,..

    Are ruined by modern fuels.

    Sometimes fumes are all it takes.

    The local pee used to eat powdercoating.

    ....Cotten
    Last edited by T. Cotten; 10-18-2019 at 12:56 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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