in"sight" to the 990 Fuel pump

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Vicks, May 7, 2009.

  1. gefr

    gefr Life is a trip

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    Everything works great. The tea bag filter samples came just before July so have not had the opportunity to test them. A broken leg holds me back. I estimate a cost around $35 + postage including the big oring in case somebody damages it. Cheers.
  2. Vicks

    Vicks gets stuck in sand

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    best wishes and good luck on your broken leg. heal well.

    the 35$ price looks really good and i'm sure a lot of people will appreciate the efforts you have put in to get this reach fruition. :clap :clap
  3. doglegdon

    doglegdon doglegdon

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    Hi guys, have always been a bit of a lurker, but read this entire thread from start to finish with great interest and would just like to share my experiences with the filter problems on my 2008 990 S.
    I live in the Philippines, (UK expat), I've had my bike since new, about 23k kms(14500 miles+/-). I'm now on my 4th set of filters. Our fuel here, leaves alot to be desired.... High water levels, (condensation in gas station tanks), rust and other UFO's are but a few of the worries we have. The fuel is also up to 10% bio-ethanol which I'm sure doesn't help this type of problem either.
    I've had the usual loss of power scenario many times and always with the same results, change filters, bike runs like new again. The sock filter is always brown and gritty, I'm wondering whether this is something to do with the bio-ethanol content? The paper filter doesn't look too bad, but when the metal end caps 'drop off, the plastic filter holder is always burnt in the middle, anyone know why or have experienced the same?
    I just bought a slipstream filter net, (as someone put up on a previous page), for more off the beaten track gas stations when filling up, but I'm still in a quandary as to what to do about the internal filters.
    I really like the idea of an easy to get at, external filter on the way to the injectors, a 10 micron one, I guess. I know this is a really stupid question but do you really think the fuel pump needs the in tank filters, (especially if you filter the fuel, seems like a lot of hassle taking off your tank, empty the damned thing, remove the pump, change etc., etc?
    You might say that obviously KTM wouldn't have put them in without good reason, however, I bought two filter sets from a friend coming back from Austria last week(US$100/set after discount, half price of how much they cost in Philippines), but I too had the same problem with the new style filters that wouldn't fit. I 'tapped' it on with a rubber mallet to get the sock one on. Like other guys, I'm really surprised that if they(KTM) charge you an arm, a leg and your first born for a set of filters, surely they could check that they 'fit without force', on the pump. Anyway, I reassembled the pump, and found I had no parts left over, which for me is pretty good....!:D
    I'm currently respraying the bike to the 2011, 30th Dakar anniversary colour scheme, so it'll be a week or two before I put the bike back together and find out if the fuel pump works.:huh
    P.S. The viton 'O' rings for the pump/tank connection (60mmx 3mm), I bought 2 for P74 (or US $0.88/each), KTM can bugger off if they think I'd pay their prices.
  4. Vicks

    Vicks gets stuck in sand

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    hi doglegdon,

    the intake filters are not exactly 10micron. thats the roung paper filter which is pre-injector. The sock filter is something like 30micron and there to prevent debris/junk from getting into the blades of the turbine impeller style fuel pump. If you remove the sock filter, this crap can wear out the intake side of the pump.

    My end goal with this thread is to reach a solution to simplify this complicated KTM FI pump setup using easily/cheaply available auto parts while making it an external fuel pump setup for easy trouble shooting / maintenance.
  5. doglegdon

    doglegdon doglegdon

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    Thanks for the reply Vicks, I really appreciate all your efforts & research you've put in to do this. (Seen in the last 18 pages of this thread.) However, I'm getting pretty desperate nowadays and just wondered if by pre-filtering fuel, running the pump itself without filters, putting in an external +/-10 micron filter between the regulator and the injectors, could be achievable and easier to maintain without damaging the pump itself.
  6. Vicks

    Vicks gets stuck in sand

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    I think pre filtering the fuel will help to some extent, but slow down your tank refill process.
  7. Autostream

    Autostream Long timer

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    Having just replaced my 3rd filter set and based on my observations and original hunch it was pump cavitation I believe the filter sock is just too damn good.

    Seems it blocked originally with paint over spray in my tank (or so it looked first time to me) and the last two was crap in the fuel, this last time mostly very fine rust.

    This time I looked at the filters very carefully and opened them up. The filter sock was chocka block full and blocked with very fine rust that turned to dust when dry, the filter proper on top of the pump had no trace of anything in it and seemed very clear..

    If the finer particles got through to the second filter the pump has more ability to push the fuel through without ill effects, but if the primary filter starts to become blocked then the low pressure on the suction side starts the pump cavitating, particularly as it, or the fuel gets warm.

    The filter being good I see as no issue in a perfect fuel world, but IMHO it is simply not big enough to cope with the harsh realities of the fuel we are sold, or forced to use out in the back of beyond. If it were beiiger it may actually drop some of the sediment, but I suspect the surface area and flow keep all it catches firmly sucked to it.
  8. gefr

    gefr Life is a trip

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    I found a Chinese company, manufacturing car fuel pumps. They are rated at 3,5bar and at 90lit/hour. I imported a minimum batch of 100 units and am modyfying them to adopt in our tanks. The final product is operational and seems reliable. Mine is running flawlessly since last February. Cheers.
  9. rattis

    rattis Long timer

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    If I'm wrong....
    But is it possible to tap into the return flow from the reg and put a filter on that?
    This so that the overfow is being filtered thus filtering the whole tank on the go.
    Or eliminate the paper filter and put a much larger external filter on the outside?
  10. gefr

    gefr Life is a trip

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    There have been some thoughts on this solution but they got diverted to external fuel pumps.
    Cheers.
  11. RoundOz

    RoundOz Plenty of seasoning

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    Not sure if covered earlier here but some guys seem to swear by the filter cleaning mod, which reverses the pump on shutdown to blow out the pre filter. CJ sells them, which puts it several notches higher on the believability scale for me...any experience here?
  12. gefr

    gefr Life is a trip

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    But then it is a personal choice.
    Cheers.
  13. RoundOz

    RoundOz Plenty of seasoning

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    Changing filters is not a five minute job and not one you want to do on the side of the road...the purge kit is designed to make the intervals longer between having to replace filters, maybe negating the need to change filters at all, depending on how well the system works and how poor the fuel quality is. I have seen the same principal applied to 400 kW pumps used in underground mining. On shutdown the normal checkvalve is bypassed for a certain period to flush out the suction screen on the priming pump. From CJ's website:

    We have a few test riders use them over the last few years and many thousands of miles. Reports back have said there filters are still looking in great shape, when they would be dark by now. They are still in there bike now.
  14. fredbenz

    fredbenz 2 wheel adventurer

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    Don't know if anyone is still paying attention to this thread... ?

    From reading through it I'm convinced that the issues I've had with my '07 990 are due to the 'cavitation' issue with the pre-filter, (thanks to "Autostream" for his explanation).

    My next step is to get the rebuild kit (O-Rings seperately). No issues there.

    My question is if/when it occurs again... i.e. the teabag/sock intake filter gets clogged and cavitation starts again, is there any way to clean that filter even if only as a temporary fix or is the case that once it gets clogged with debris the only choices are to either replace it or remove it (temporarily).

    Appreciate the thoughts/experience of those who know more
  15. KTMbageera

    KTMbageera Adventurer

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    You might consider CJ Designs fuel filler filter upgrade. I installed the new filler necks with pre filters on my 09' 990R and they really extend the service life/frequency of my filters. + they look cool.



    https://www.youtube.com/watch?v=uEI2Ancvd3w
  16. guglemonster

    guglemonster Crivens!!!

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    hallo fredbenz

    if you have the new prefilter from ktm, left on the image, right the old plaastic membrane type

    [​IMG]

    you can wash it with a solution of fuel injector and clean petrol, light mixture, let it soak for some 20 minutes, blow it from inside, dip again and repeat 3 times, it will get 80/85% as good as new

    as prefiltering, the original ktm is not selective enough to preserve the original filter set

    it's only monolayer and far too expensive, far too much
  17. rburkat

    rburkat Been here awhile

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    I recently took apart my 990 fuel pump and tested it on the bench. I tested about 40psi going forward so my pump is not doing too hot, but I particularly tried reversing the polarity on a primed pump and I saw absolutely no flow or any type of pressure in reverse. So reversing the pump to blow out the filter seems like it would not do much.
    Am I missing something here?
  18. bikyto

    bikyto Dans le doute...gaz!

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    I have the reverse mod done. I was the Guinea pig for CJ's version several years ago. You need to remove the one way valve that is inside the pump so that it can free flow back into the filter when reversing polarity. There is another one way valve provided to add inline to the fuel line.
    I'll see if I can dig out the pictures.
  19. rburkat

    rburkat Been here awhile

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    Was this on an external 950 pump or the 990 efi that we're talking about here?

    Here are videos of my testing....




  20. bikyto

    bikyto Dans le doute...gaz!

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    Yes Radek. On an internal 990 EFI fuel pump for my 990Adv