Gas Tank Geyser!


7 replies to this topic
  • story_rtw

Posted July 12, 2005 - 07:09 AM

#1

Anyone had this happen?

I was riding this warm weekend at about 8,000 feet, after installing my new gas cap vent valve. At one point we stopped and I noticed that gas was flowing out of my carb overflow tube, so I shut off the fuel valve and the trickle stopped. I wondered how much gas I had actually lost, so I opened the gas cap to take a look. I unscrewed the cap and immediately gas shot about 3 feet into the air! :applause: The geyser continued for several seconds until it slowly subsumed back into the tank.

Of course at this point my entire bike was covered in gas, not to mention my hair and face. I washed off things as best as I could, and rolled the bike away to let the gas evaporate before starting.

I've never heard of this happening before. My guess is that the gas in the tank boiled from the heat and pressurized the tank. The vent valve must be a one-way valve that lets air in but not out. When I opened the cap, the extreme pressure forced about a gallon of gas to shoot from the tank!

Next time I'll be a lot more careful when I remove that gas cap!!!

Story

  • Indy_WR450

Posted July 12, 2005 - 08:51 AM

#2

Sounds like your gas tank was boliing the gas in it. Do you have an oversized tank that is too close to the header or engine ? :applause:

  • story_rtw

Posted July 12, 2005 - 10:17 AM

#3

Sounds like your gas tank was boliing the gas in it. Do you have an oversized tank that is too close to the header or engine ? :applause:


Yup, I've got an Acerbis tank with a stock exhaust. I thought I mounted everything according to instructions. Still, I agree that the gas must have been boiling.

Here's another thought. If the tank was pressurized enough it may have inhibited the gas from boiling (just like a pressurized radiator) until I removed the cap and reduced the pressure, at which point the gas boiled (quite quickly and violently!)

The good news is that I rode the rest of the day without any subsequent problems.

Story

  • Indy_WR450

Posted July 12, 2005 - 12:08 PM

#4

I have the same tank. GYTR (Acerbis 3.3/3.4 gallon) and you have to heat tape wrap the secondary petcock and fuel line. It is close to the head and the header that it will boil the gas on hot days. :applause:

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  • trickwarrior

Posted July 12, 2005 - 01:12 PM

#5

Is your breather installed in the right direction? That pressure should be leaking out the gas cap breather. They are a one way valve. Good Luck :applause: <M>

  • 450g-ride

Posted July 12, 2005 - 03:38 PM

#6

Re: Gas Tank Geyser!

Sounds like your gas tank was boliing the gas in it. Do you have an oversized tank that is too close to the header or engine ?


If the gas was boiling - and it splashed on you like you said it did you probably wouldn't have a face anymore. gasoline boils at very high temperatures. It must have been a pressure issue.

  • Indy_WR450

Posted July 12, 2005 - 03:47 PM

#7

The boiling point of gasoline is around 200F depending on Octane rating. The temperature at which gasoline combusts is around 536 F at atmospheric pressures. :applause:

  • WheelsUp

Posted July 12, 2005 - 07:37 PM

#8

Is your breather installed in the right direction? That pressure should be leaking out the gas cap breather. They are a one way valve. Good Luck :applause: <M>

No, it was installed the right way. If it were a one-way valve and vented OUT, then as fuel level dropped, it would form a vacuum in the tank and stop fuel flow.

It's an emissions thing... the pheds don't want your tank to vent to the atmosphere.

Pull the check valve, then secure the vent tube to your handlebars with a fuel filter on the end to keep from sucking in dirt.




 
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