DIY: Charcoal Canister Removal on F800GS (with pictures!!)

Discussion in 'Parallel Universe' started by Y E T I, Aug 28, 2009.

  1. Singletrack_mind

    Singletrack_mind Cave Man

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    For me, this little valve is the smoking gun. I experienced the water-uptake through the original non-T'd vent hose, A second vent in the manner of the BMW recall fixed that. The issue I still have on occasion that I suspect may be caused by this little valve is that a huge amount of pressure can sometimes build in the tank. At one point I opened a recently filled tank and fuel exploded out all over me. What I suspect is that sometimes a bit of fuel reaches that check valve and stops it up, then the pressure that builds inside the tank can be really serious. Erling's experiments suggest to me that it might be good to arrange for that little valve to point up somehow, so it is 'self bailing'. I've played with it my self and it is really picky, it locks up solid very easily. I've previously thought about just removing it all together. Why would you ever WANT 5psi in your fuel tank, especially if it's an entirely variable parameter? If it were removed though, the tip-over valve would be the only defense against liquid fuel reaching the CC, so it'd probably be better to help the valve work the way it was intended.

    we've seen that the valve is the same on the Euro bikes, the only difference is the presence or absence of the CC. I wonder though if the hose that carries that check valve lies differently on the euro bikes, since it's running to the bottom of the bike rather than to the CC? from what I remember, (and I can't look at my bike right now), it doesn't seem like it should be any different, but maybe?
    #81
  2. ebrabaek

    ebrabaek Long timer

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    I agree with single.... That check valve is made to work in conjunction with the suction created by the manifold vacuum when the purge valve opens. You see... the pressure needed to open said check valve from the tank and out..... is not needed. As soon as the slightest vacuum is applied to the side away from the tank it opens and vents. Basically...there should never be so much positive pressure in the tank that you can hear a swooooosh when its opened. This is speculation on my behalf..... But... I think it will hold up.....:thumb:thumb

    Erling
    #82
  3. Y E T I

    Y E T I Unpossible

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    I've felt this was the real culprit of tanks splitting over here for quite a while. I haven't removed it, yet, but I may.


    What do you think the downside of removing it would be?
    #83
  4. ebrabaek

    ebrabaek Long timer

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    None..... I can n ot come up with one reasonable answer as to why BMW want's up to 5 psi in the tank. I have asked several tech's.... and got answers like.... " in case fuel goes in there due to an overfill of the tank....then that valve will close"...... But then explain how the CC get's saturated with fuel.....:wink:.... On bikes before the CC vasectomy.... There will be pressure on the tank when the bike sits in the sun with the engine off....... Only the engine's consumption of fuel..( which is not much since there are not a fuel return at the injector stations) and the opening of the purge valve ( applying a slight vacuum on the top of the Carbon plug in the CC) will alleviate the positive tank pressure. I have tried both..... All I observe..... Is the garage smells more of gasoline due to more vapors escaping when I park it after a ride....... Than when the valve is installed..... But there are no more smell than when I park the smaller DS rides.....
    IMHO.... NOT NEEDED......:thumb:thumb

    Erling
    #84
  5. Singletrack_mind

    Singletrack_mind Cave Man

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    #85
  6. señormoto

    señormoto Supermoto Abuser

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    All of the talk so far seems overly complicated - tanks have had vents/valves for overflow and tip over for decades and they've (almost) never had the issues that the F800GS is having. My vote it to try out a standard MX style valve and see what happens when the bike is on its side. I might have one lying around in the parts bin somewhere...
    #86
  7. Singletrack_mind

    Singletrack_mind Cave Man

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    I agree, real experimentation is what we need. Let us know what you find out.

    I'm not so worried about what happens when the bike's on it's side though, since the fuel tank pressurization happens in all sorts of situations where the bike hasn't been crashed. The tip-over cut-off inside the tank should keep fuel from flowing into the vent tube when the bike's down.
    #87
  8. ebrabaek

    ebrabaek Long timer

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    Just wanted to mention that in addition to removing the check valve.....I removed the CC as well. I have not tested the functionality of the valve when liquid enters it..... But have heard by many that that is a function of said valve. We have heard countless times about overfilling the tank....and that one should not do that..... In connection with the F/I issue.... So somehow that theory is not bullet proof... Simply because if this valve would prevent fuel from going into the CC when the tank is overfilled...... with so many riders doing exactly that......it proves that said valve in fact does not keep liquds from entering the CC. All that said..... I was nervous about me goofing and overfilling the tank....and would overflow into the area under the seat, where I have the vent...and filter. So I deliberately filled the tank to the tip top.....and closed the cap....rode around the neighborhood to see if I could spill the fuel....... And even after sitting for a while...... Nothing came out. I have had mine off for about 18 months now.....ridden through some rough stuff......but all I get is a small sheen of dirt around the filter under the seat which I just clean periodically. Works well for me......:thumb:thumb

    Erling
    #88
  9. ebrabaek

    ebrabaek Long timer

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    Bingo.... When I was running the valve...... That is what I did.... Note the angle of the filter....
    [​IMG]

    :thumb:thumb

    Erling
    #89
  10. Sock Monkey

    Sock Monkey 99% bullshitter...the other 1% is just lies

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    Have you ever experienced "surging", or generally poor fueling at low throttle openings, especially over rough ground? Now take a look at the diagram on page 1, and note that you have a relatively direct path from the fuel tank to the throttle bodies (via the canister). On every bike I've owned with these warts, I've had this same surging issue at low throttle openings (my Guzzi was the worst in this respect).

    The cause is because as fuel sloshes around in your tank, some of it (and certainly the vapors, or partially evaporated fuel) gets sucked right into the throttle bodies and added to the fuel mix that had previously been oh-so-carefully metered out by a very sophisticated system of fuel injectors, sensors, and computers. As a result, you get randomly rich mixtures going kaboom, resulting in less-than-ideal performance. I give BMW credit for trying to minimize this via the pressure valve, but as you all have seen, that can cause other unwelcome issues (cracked tanks, fuel baths, etc.). Remove the wart, and these problems go away (at the expense of fuel vapor entering the atmosphere....but that's a whole 'nother bucket of worms that won't be solved until fossil-based fuels are eliminated :gerg ).

    -SM
    #90
  11. JRWooden

    JRWooden Long timer

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    Has anyone figured out what is done on non-USA bikes with the tap on the tank that would connect to the CC?

    Is it simply capped off?
    #91
  12. Singletrack_mind

    Singletrack_mind Cave Man

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    Post #30, page 2.

    The valve is still there, but the line it's in just vents to atmosphere instead of going into a carbon canister.
    #92
  13. JRWooden

    JRWooden Long timer

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    STM:

    Sorry I'm confused .... it's saturday...
    Here' is the picture for USA bikes of the tank ... it looks the same to me?

    tank1.jpg

    See next post for other picture ... since I can only upload one picture per post....
    #93
  14. JRWooden

    JRWooden Long timer

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    Here is the CC layout on US bikes ... on Euro bikes what happens to the tank fitting to which #9 is attached, or does that attach somewhere else the fiche is not too clear on that ..............

    tank2.jpg
    #94
  15. 'Flagger

    'Flagger ..this space for rent..

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    #95
  16. Y E T I

    Y E T I Unpossible

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    My understanding is that the line (#9) leaves the tank, goes through the little valve (#8) and then runs to where I have my filter where it vents to the atmosphere.
    #96
  17. JRWooden

    JRWooden Long timer

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    Wow... so they use TWO of the "ventilation valves" P/N: 16117721943 ?
    Item #8 in the CC diagram, and item #17 in the tank diagram....
    Item #17 being downstream of the tip-over valve and item #8 being connected directly to the tank ....

    That kinda makes my head hurt ... more .... I think it is time for ....... :slurp
    #97
  18. Singletrack_mind

    Singletrack_mind Cave Man

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    I'm pretty sure that "Ventilation valve" (PN 16117721943) which appears in both the carbon canister diagram and the fuel tank diagram is actually the same piece. It certainly bears the same part number, and I am not aware of that valve being in two places on my bike. I think it's just a question of how the parts diagrams are drawn up. The exact same tank diagram is used for the euro model, so it has to include the valve, but in the USA they add the Carbon Canister diagram and include the valve again because it's part of the system. Just a little overlap.
    #98
  19. Y E T I

    Y E T I Unpossible

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    Exactly. There's just one valve.
    #99
  20. JRWooden

    JRWooden Long timer

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    Ok my last stupid question for today:

    So, what we're saying is that the hose that is shown as #18 in the tank diagram is the same as #7 in the CC diagram (for USA bikes)?