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Thread: Fuel Tank Venting Problems

  1. #1
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    Fuel Tank Venting Problems

    Ran my bike a couple of days ago for a couple hours. Bike is 1986 R80; no suffix. All normal. Filled up gas
    tank enroute my home and thereafter it was just a couple miles to home. Parked bike in garage and next day
    found gas weeping from the vent (apparently) at the front top of the engine. Has anyone experienced this before?
    Admittedly tank was quite full, but have done same before and no issues. Garage is large metal-roofed building
    that does get fairly hot inside. Could the gas merely be expanding and the tank venting normal? I haven't pulled
    the tank recently. I did, however, update all the mounting grommets and the front rubber deal under the tank. That
    has been a few weeks. At the time all was fine. Anybody????????

  2. #2
    Administrator 20774's Avatar
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    Just sounds like a too-full tank situation. My /7 has a drain tube that takes fluids down the right side to the ground. I think it's meant for rainwater that collects in the well around the neck...it could also let any fuel drain during a gas station stop if you got it too full. I don't think it's necessarily meant for this type of overflow.

    Does the '86 have the in-tank flapper? Wasn't that included to keep people from filling too full...of course, it reduced the amount of gas in the tank which equated to loss of range.
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    Greetings Kurt. Yes, it does have the flapper. I have never had this happen before and I may well have
    filled too full. Plus, when I moved the bike off the center-stand it appears the shifting movement caused some
    gas to weep from the fill vent hose. The tank is very full as I only ran a couple miles to my home since filling-up.
    All is fine with bike just sitting still on the center-stand.

  4. #4
    Registered User helmut_head's Avatar
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    Hey Captain

    CaptainMako,

    My gosh, if it seems to be from the top of the engine where you see gas, make sure your vent tube is hooked to your tank. That overflow fuel is supposed to safely hit the ground, without any hot exhaust in between its safe path of travel. Be safe!
    Helmut always wears a Helmet.

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    Quote Originally Posted by helmut_head View Post
    CaptainMako,

    My gosh, if it seems to be from the top of the engine where you see gas, make sure your vent tube is hooked to your tank. That overflow fuel is supposed to safely hit the ground, without any hot exhaust in between its safe path of travel. Be safe!
    I'll be draining and pulling tank today. Will let you guys know what I find. Thanks all.

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    UPDATE: Removed petcocks and pulled off tank. Problem: no hose on the tank overflow. It fell off so a little venting of gas going
    of the engine top. I'm going to connect hoses to both nipples on tank and run them down where the battery vent hose used to be. Have gel battery now.

    While in the top of engine going to remove all of the Shed Fuel System. Anyone have a link on how to remove or is it self-explanatory?
    I did search on this site and couple others. Nothing specific.
    Thanks in-advance.

  7. #7
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    Something to keep in mind when fueling: Nearly every gas station's tanks are underground, so when it goes in the tank, its 60 or 70 degrees. When you put it in a steel tank that sits right above a hot engine or sits in the sun, the fuel temp goes up and so does its volume. Doesn't really matter if you're running down the road, but when you park right after filling up.....

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    Quote Originally Posted by 44817 View Post
    Something to keep in mind when fueling: Nearly every gas station's tanks are underground, so when it goes in the tank, its 60 or 70 degrees. When you put it in a steel tank that sits right above a hot engine or sits in the sun, the fuel temp goes up and so does its volume. Doesn't really matter if you're running down the road, but when you park right after filling up.....
    Point well taken. Thanks.

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