What's missing?? 800GS Fuel Pump

Discussion in 'Parallel Universe' started by Girthy Knobkers, Nov 29, 2012.

  1. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    I am of course speaking of this empty threaded hole on top of the pump here. My 800 is skipping when fuel gets around 1/3 of a tank. Pulled the pump to find that empty threaded hole...????
    #1
  2. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    I have also dug around the tank trying to find the culprit but no luck... I know that suggestion will come up :1drink
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  3. JRWooden

    JRWooden Long timer

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    Hmmmmmmmmmmmmm
    Sorry I have some pictures of the fuel pump assby. scavenged from other threads, but none show close-up of that area... I don't what it is...
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  4. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    From what I gather it is some sort of spring/valve contraption. I tried to scavenge a similar part off an old RT pump but they are two dif pieces. The only way to get that is to order a whole new pump! :ddog
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  5. njoytheride

    njoytheride NJOYN' THE JOURNEY

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    I purchased the after market pump off of Ebay. I will look tonight and see if it has something located in that area. I took pictures of the OEM pump assembly when I was checking the filer but no pictures showed the top of the pump.
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  6. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    Thanks, I understand that BMW is really good at manufacturing a part that works on many bikes and that hole might be something that on another bike has something in it but the 800 never did. Knowing would help eliminate the reasons for this skipping at 1/3 of a tank or lower...
    #6
  7. docsherlock

    docsherlock Been here awhile

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    Your pump is probably overheating as the fuel level drops; the fuel is also used for cooling the pump. Many references to this symptom and cause on the forums.

    If there was nothing in the tank, I doubt your pump is missing anything.
    #7
  8. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    So replacing the pump is the only option? what is causing it to over heat?
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  9. ebrabaek

    ebrabaek Long timer

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    How did your fuel filter look....????? I live in the desert, with over 100 deg. on a regular basis, No issues after 12000 miles with running the tank down. It would make sense to me that if your filter had a partial blockage, then as fuel level dropped to 1/3 pump has to siphon too much, and fuel starvation occurs....imho.
    #9
  10. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    I back flushed it and a lot of gray gas came out, now I am beginning to flush it forward and the gas looks even worse... going to keep flushing...
    #10
  11. JRWooden

    JRWooden Long timer

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    GK:

    While you have that filter on the bench would you mind capturing the dimensions of it?

    Diameter & height, and length and diameter of nipples?

    The local NAPA parts store manager is a buddy of mine maybe he can reverse engineer something that would work...
    Its a frigg'n FI-rated fuel filter damn pity that BMW won't sell us one separately..........
    #11
  12. Girthy Knobkers

    Girthy Knobkers Running on reserve

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  13. JRWooden

    JRWooden Long timer

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    Thanks! :D
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  14. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    let me know, I got a look at an oem replacement and it seems nothing goes in that hole that I was curious about. The pump over heating makes sense as well as the fuel filter being dirty. If there is a filter that can be wedged in there that would be sweet
    #14
  15. JRWooden

    JRWooden Long timer

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    Will do, I'm not real optimistic, but we could get lucky....
    That would be nice............
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  16. docsherlock

    docsherlock Been here awhile

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    I think what happens is that the fuel filter gets blocked so the pump has to work harder to pressurize the fuel and is then prone to overheating - drive any electric motor too hard and it will overheat.

    So I agree that replacing the pump and filter assembly will probably fix the problem but if you can get a separate new filter that is likely the root cause.
    #16
  17. C5!

    C5! Been here awhile

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  18. njoytheride

    njoytheride NJOYN' THE JOURNEY

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    The Highflow after market pump has a hole in the same location and it looks like that is fitted in from the back side. Maybe a pressure relief valve ? Not sure. It appears to be ported. hmmm??
    #18
  19. Indy Unlimited

    Indy Unlimited Long timer

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    You got to have a blow off for excessive pressure back to tank. So that makes sense.
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  20. Girthy Knobkers

    Girthy Knobkers Running on reserve

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    I have decided to go with the external filter route. Does anyone have a part number for a filter that is 10 micron rated I can pick up at a local auto parts store?
    #20