KTM 990 Adventure Fuel Starvation while Low on Fuel?

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by BillyD, Jun 1, 2010.

  1. BillyD

    BillyD Been here awhile

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    Before I started diving into it, I thought I would bounce this off the experts...

    I picked up a 2008 KTM 990 Adventure S recently and have hit reserve twice thus far. Both times, the bike seemed to be starving for fuel while the reserve light was on.
    <o:p> </o:p>
    For instance, it would hesitate under acceleration, especially above 5,000 RPM, and pop noticeably while decelerating. My KTM 525 does the same thing just as I need to switch the petcock over to reserve.
    <o:p> </o:p>
    To me, this suggests that either the tanks are not vented properly or fuel isn’t getting from the right tank fast enough even though both petcocks are open. If it were the fuel filter, I would expect fuel starvation regardless of fuel level. If it is tank venting problem, I would expect starvation to get progressly worse as fuel level in the tanks dropped due to the greater air volume.
    <o:p> </o:p>
    When I opened the gas caps at the gas station, I didn’t hear any in-rush of air, but there was a noisy diesel truck idling nearby so I may have just missed it. After refueling, the bike again ran the same as it did before hitting reserve (i.e., no hesitation while accelerating, no popping on decal).
    <o:p> </o:p>
    This bike has the canister, SAS and servo controlled butterflies removed. It has Akros and I’m told the Akro map loaded; however, I don’t know which particular Akro is loaded.
    #1
  2. flytier

    flytier Refusing to grow up

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    You might have a bad fuel sensor and its actually giving warning right as tank is on empty............
    #2
  3. BillyD

    BillyD Been here awhile

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    Thanks, flytier for the thought which highlights information I forgot to provide.

    On both instances, I refueled within 8 miles after the reserve light came on and it took approximately 4.1 gals each time. This suggests to me the fuel indicator is functioning properly.
    #3
  4. Jhalls

    Jhalls Been here awhile

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    Hi, I just did a 4000 mile ride on my 990 last week, I went from ATL GA into Moab Utah and back to ATL in 9 days. While on my ride my brother had this exact problem. He also has a 990, he would burn about 100 miles of gas and it would start to play up. Anything over half throttle at about 5000 rpm and the bike would hold up, hesitate, pop and crackle badly on deceleration and be a general pain in the arse, it seems the weight of the fuel on full tanks was enough to push the fuel past the crap in the filters even with a pressurized system it still needed the weight of all that fuel in a full tanks to work properly.

    When we got back into town on Sunday we rested but on Monday he pulled it apart to find his fuel filters where shot. He took the filters to the local KTM dealer and they also confirmed the filters where well shot and needed replacing.

    Hope this info helps.
    #4
  5. shawty950

    shawty950 Been here awhile

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    +1 on this...same issue on my 07 990S.

    Shawty
    #5
  6. minusone

    minusone Long timer

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    I have had this issue on a numbner of times (out the back of mount horrible as darkness approaches - rescued by hillbillies on that one) It gets so bad bike does not climb even simple grades.

    Fuel filters was always the problem.
    #6
  7. Englishmatt

    Englishmatt Been here awhile

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    I am the said brother form Jhalls. Fuel Filters are 100% problem. They'll cost you $120 for the replacement kit (three (3) filters.

    What happens under low fuel, above 5K RPM and more thna 50% throttle with blocked filters the pump can't pull the required fuel through quick enough. One of the side effects is the fuel begins to boil...

    When you fill up, you'll add cold fuel, stopping the boiling, and the heat coming into the left tank isn't enough to boil 3 gallons but is enough to boil 1 gallon.

    The surging you feel is caviatation of boiling fuel going through the pump.

    Whilethe tank is off, buy soem self-adhesive heat shield (KTM actually make a sheet of the stuff for the dirt bike that is self adhesive and enough material to cover your entire bike) for $25.

    I'm willing to bet this happened to you on a WARM day......right?

    Hope this helps....
    #7
  8. BillyD

    BillyD Been here awhile

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    Thanks one and all...this is why this site is so helpful.

    I will change the filters and heat protect the tank.

    On a separate note, I have actually seen gas boil in an unprotected 525 tank.

    Tanks [sic] again!

    Bill
    #8
  9. Gluaisrothaí

    Gluaisrothaí Feckin' gobshite

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    Englishmatt is 105% accurate here. I've had the same symptoms in the same situation, with the same resolution. Fuel heat, blocked filter, pump cavitation and hesitation.


    #9
  10. AdvGa

    AdvGa Long timer

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    If I had a 990 / fuel pump in the tank, I would keep the Gas Level up at least above 1/4 Tank as much as possible, Especially during the Summer,
    to keep the Heat Stress off the Fuel Pump. This will also help keep the debris out of your Fuel Filter.
    #10
  11. BillyD

    BillyD Been here awhile

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    This will be a side benefit of the advtank rear tank I'm in the process of adding.
    #11
  12. Hipster

    Hipster Long timer

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    What's included in the 990 fuel filter kit to make it worth $120 :eek1
    #12
  13. Englishmatt

    Englishmatt Been here awhile

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    What makes it $120 is there are actually three (3) filters in the Fuel Pump.

    1.) Normal looking Fuel Filter in the Regulator Valve
    2.) Sock/Screen Filter that it outside of the fuel pump enclosure
    3.) Very small interla filter/screen that goes from the fuel pump to the regulator valve.

    Then there are seals etc... It's the Fuel Filter(s) Replacement Kit.
    #13
  14. Englishmatt

    Englishmatt Been here awhile

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    Oh, and "keeping the fuel above 1/4 tank in the summer" is a laughable solution/suggestion. In theory, it's ok....but when you pay top dollar for this bike, there's principalities involved smokey!

    This is an Adventure bike. The V-Strom already easts this thing up for fuel economy. Stopping every 100 miles to keep the tanks topped off, to avoid the bike quitting due to a dodgy fuel pump is simply not a workable solution.

    Replace the filters....it's cake....
    #14
  15. Hipster

    Hipster Long timer

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    So it's an all inclusive filter kit, no additional seals need to complete the job correct?

    #15
  16. Andreas240

    Andreas240 Adventurer

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    Yup - same symptoms and same solution. Replaced the fuelfilters and everything was back to normal. :jump

    Englishman, thanks for the explanation. :thumb
    #16
  17. BillyD

    BillyD Been here awhile

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    Got the tanks insulated.
    <o:p> </o:p>
    [​IMG]
    Left Tank.
    <o:p> </o:p>
    [​IMG]
    Right Tank
    <o:p> </o:p>
    [​IMG]
    Cutout Patterns for Left Tank
    <o:p> </o:p>
    Now to replace the fuel pump filters. Looks like someone has previously replaced the filters based on the presence of excess sealant around the base of the fuel pump.
    <o:p> </o:p>
    #17
  18. Vicks

    Vicks gets stuck in sand

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    got a link for manuf/source of the heat shield material you bought ?
    #18
  19. BillyD

    BillyD Been here awhile

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    Vicks:

    It's Moose Racing Heat Shield material that comes in 18"x18". I sourced it locally, but it should be readily available at any number of online retailers, including Amazon:

    http://www.amazon.com/Moose-Racing-Heat-Shield-Sheet/dp/B001DDAA30/ref=sr_1_1?s=automotive&ie=UTF8&qid=1277014489&sr=1-1

    The reflective tape I used to seal the edges and seams is available from Home Depot. It comes 2" wide, but I cut it into 1" strips.

    http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?jspStoreDir=hdus&catalogId=10053&productId=100318556&navFlow=3&keyword=884281&langId=-1&searchRedirect=884281&storeId=10051&endecaDataBean=com.homedepot.sa.el.wc.integration.endeca.EndecaDataBean%4020932ccb&ddkey=Search

    If you don't have a local source for the tape in Jordan, let me know and I'll send you some. PM me a ship-to address. Maybe the tape and throttle butterfly valves will pass each other in opposite directions.
    #19
  20. Vicks

    Vicks gets stuck in sand

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    sorry Bill, i didn't recognise it was YOU !!!

    I got the butterfly valves and screws packed and will be going to the post office in a short while.

    I'll go have a look at the local hardware stores and see what they've got...
    #20