990 Fuel Pump Won't Seal

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Mikef5000, Dec 4, 2013.

  1. Mikef5000

    Mikef5000 Long timer

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    My (2008 990) fuel pump has been leaking for months. Usually just a couple drops a day, so I've ignored it and parked over a piece of cardboard.

    I finally got around to tackling it yesterday.

    The pump was stuck pretty good, but after much coaxing, I freed it from the tank. The original O-rings (36k miles) were swollen and ugly, but not noticeably torn.

    I spent probably half an hour cleaning the hardened amber 'fuel' from around the hole in the tank and the base of the fuel filter; I got it all quite smooth and clean. I replaced both O-rings (as well as both filters), lubed it up with Vaseline, and pressed it back in. It was a tight fit, so I used the 4 bolts to pull it flush (going around in circles tightening them a quarter turn each time. All seemed well.

    I threw everything back together, went for a 10 minute ride, and parked it.

    An hour or so later I notice a small puddle of gas beneath it. I saw dropplets hanging from the pump bolts, the bottom of the pump, and running down the skid plate beneath the pump.

    Tore it all down again, and popped the filter back out. The O-rings looked and felt perfectly fine.

    This time I lubed it up with a gasoline rated, non-hardening gasket slime. I pressed it back in extremely carefully, making sure there was no way I dislodged the O-ring. Buttoned it back up, threw gas in, and another 10 minute ride. All seemed well again, and it sat overnight without leaking.

    Today I went out for a ride. After 45 minutes I checked it and everything was bone dry still.

    An hour and a half later, it's dripping again. Again, dropplets hanging on the fuel pump bolts, so I'm quite confident that's where the leak is. It does not look like anything else in the area (hoses/barbs) could leak and accumulate gas where I'm seeing it.

    So I've got it back apart again and I've wiped all the remaining lube/slime off everything. The plastic in and around the tank hole is smooth. The O-rings still look brand new. The O-rings came from CJ Designs.

    I've been tightening the 4 bolts as much as I feel confident, knowing they're in plastic. I know I'm compressing the O-ring, and I see the lube press out on all 4 sides. But I'm very hesitant to really crank on them.

    Not really sure where to go from here. Any advise? Tips?
    #1
  2. Mikef5000

    Mikef5000 Long timer

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    Unrelated to the leak... I just foun this in the bottom of the tank:
    [​IMG]
    Small plastic tube, threaded on one end, filter material on the other. Was it a part of this fuel system? Or did the previous owner drop it in the tank?
    #2
  3. Dusty

    Dusty Long timer

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    Mine were both off the petcocks floating around.

    [​IMG]

    As for the leak... how does the threaded serts in the bottom of tank look, could it be from one of those?
    I use a nut driver not a ratchet when i button mine back up, never had any leakage yet. Sounds like you got the o-ring in OK and properly lubed, you know when the first one slides in.
    #3
  4. gefr

    gefr Life is a trip

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    So I would think this is where you should concentrate your attention. I would also like to ask if there is any little cracks at the fuel pump base, or at the metal parts?
    Can't think of anything else.
    Cheers.
    #4
  5. injun

    injun Been here awhile

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    Mine started leaking at 10K mi tried new O rings didn't work ended up using permatex the right stuff not a drop in 7,500 mi, the round hole wasnt round.
    #5
  6. Gabby

    Gabby Been here awhile

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    Mike, I didn't know that you had a 990. Is this what you replaced the Super T with? Gefr can hook you up with filters and O-rings while you're in there poking around. Great product.
    #6
  7. Mikef5000

    Mikef5000 Long timer

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    I did replace the tenere with a 990! That was around May I think... About exactly 10k miles ago. There are definitely pros and cons to each bike, but I'm generally (when the ktm isn't endlessly dripping gas) very happy with the ktm.

    Also, I did buy the filter kit from gefr before I popped the pump out. The factory filters looked alright, but it's over 35k miles, so I figured I'd knock it out. I also bought his SAS plates and air filter plate for future use. Good stuff!

    In other news, the pump is still leaking. My permatex stuff is pretty old, and while it's not supposed to harden like rtv, it's supposed to firm up... Mine is staying liquid, and seeping out with the fuel, even after letting it setup for a couple days. I'm going to buy some new stuff and try again.
    #7
  8. Rock Junkee

    Rock Junkee Been here awhile

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    Awh man that sux were pulling for you don't give up or get pissed off
    good luck
    #8
  9. gefr

    gefr Life is a trip

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    Then go for thicker o-rings. That should fix your problem.
    Cheers.
    #9
  10. satrider

    satrider Adventurer

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    Mike, I feel for you, Man. I am contemplating purchasing a 2013 990 ADV Baja, vs. a Triumph Tiger 800xc. I notice yours is a 2008 model. Is this a known problem with the 990s? If so, has KTM changed anything to resolve this problem since?
    #10
  11. jwalters

    jwalters Farkle Proliferator

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    I had the same problem with my 990. I had the left tank replaced under warranty. I was living out in San Francisco at the time and I think Scuderia West did me a favor. They said they saw this occasionally, and claimed it was due to the ethanol in the fuel not playing nice with the ABS plastic tanks. KTM provided a new left tank but I don't think this is standard practice or cover under a TSB.

    I just replaced my fuel filters and again I had a bit of fuel leakage (enough to stink up the garage but little visible evidence) so I pulled the pump and used some fuel tolerant gasket sealer around the base of the fuel pump where it meets the tank. No problems since. I just figure, I'll have to continue to add a little sealant goop around the base of the fuel pump everytime I swap fuel filters. And of course, run ethanol free gas.

    I hope this is useful.
    Jesse
    #11
  12. satrider

    satrider Adventurer

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    Jesse, what year model was your 990?
    #12
  13. jwalters

    jwalters Farkle Proliferator

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    2008 990 adv s

    #13
  14. Mikef5000

    Mikef5000 Long timer

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    The related 'known problem' is ethanol in our gas slightly distorting the tanks. This is obvious when trying to re-fit the tanks after you remove them for service; you kind of have to force them back to line the bolts up. Not a big deal at all, but noticeable.

    I figure, if the rest of the tank is slightly distorted, the round fuel pump hole most likely is as well.

    If a bead of gasket maker/sealer around the base of the pump solves the issue... then I'm perfectly fine with that solution. I'll be buying fresh gasket maker/sealer this afternoon to try again.

    All that being said, I don't think you (satrider) have much to worry about with that 2013. Perhaps after 3-5 years of using ethanol fuel you'll be in the same situation, but at that point, just start using gasket maker/sealer.

    As Gefr said... the optimal solution may be to re-round the hole with a borer something like this:
    [​IMG]
    And then go up a size on O-rings... But I'm going to start with good sealer first.
    #14
  15. Mikef5000

    Mikef5000 Long timer

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    I've got faith this time. The new gasket maker/sealer was an entirely different consistancy from the old stuff...

    I had used some gray gasket dressing or similar, but it was 3-4 years old, and very liquidy... and stayed liquidy. It's been several days, and pulling it apart, it was still nasty liquidy.

    This time I used this stuff:
    [​IMG]

    It came out thick and tacky, and quickly dried to thicker and tackier. I applied a thin layer to both the base of the pump and the surface of the tank, and let it setup for about 15 minutes (it's only about 40-45 degrees out there, so a bit longer then their recommended 'few minutes') and bolted the pump back in the tank. I figure I'll leave it on the bench to harden and seal as much as possible, before I put it back on the bike and put gas back in it.
    #15
  16. Mikef5000

    Mikef5000 Long timer

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    Sorry for the delay, but the new Permatex 2 seemed to have done the trick. The pump appears to be sealed well, and I will forever use this stuff when doing fuel pump service (which hopefully isn't often).
    #16
  17. Mikef5000

    Mikef5000 Long timer

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    5 months (and several thousand miles) later, My fuel pump is leaking again. Just enough to be noticeable on the skid plate... no drips on the garage floor yet.

    Disappointing.

    I just wanted to update this thread if others are in my same predicament. Using non-hardening gasket sealer is a good temporary solution, but doesn't appear to be a long term fix.
    #17
  18. pdxmotorhead

    pdxmotorhead Long timer

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    If its any consolation, this problem is not unique to a KTM or even bikes, cars, trucks etc with in tank pumps and plastic fuel tanks have all kinds of issues with the flanges leaking where they bolt to the tank. I just replaced my 94 jeep wranglers fuel tank gasket for the 4th time in 200K miles.. And they are like 35 bucks each.. The plastic tank on the jeep has swelling and distortion issues too .
    #18
  19. gefr

    gefr Life is a trip

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    It could be the closest to the OEM oring size (ID=60mm, t=3mm) but slightly thicker in inches. Even without boring the hole.
    Cheers.
    #19
  20. sparwood_rider

    sparwood_rider Adventurer

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    I wish I knew the root cause of this. Observations:

    - The tank hole looks warped when you look inside, but the hole's diameter is constant where the o-ring seals.
    - The flange surface on the tank is definitely not flat. When you disconnect the bolts, you can feel the tank flex. There's no doubt in my mind about this.
    - The inboard front bolt always seems to be wet.
    - Fuel comes out from under the flange on the front edge. The flange edge that faces the front of the bike.

    Trying to band aid without truly knowing the root cause...

    I've tried several of the 932's without success. I'm getting tired of pulling the tank on and off and staring at the ground under my bike looking for pools of fuel. I've tried both 75 durometer and 90 durometer. The diameter of the 932 o-rings were around 2.70 to 2.77 mm. I tried Seal All. It didn't seal sweet all even though I cleaned everything will alcohol and let it evaporate and take my time. I waited for it to get tacky… no luck. I'm currently testing the Dow Corning 55 o-ring sealant. I was able to swell the 75 durometer o-ring to 2.99 mm and then I put it back together. You can buy small containers of Dow 55 for $3 on-line. My local store wanted $80 for a toothpaste size container! I put the Dow 55 on the flange o-ring as well. It went into the tank relatively easy compared to the other trials. I put an excessive amount on both the o-rings. At this point I'm willing to try anything. I just put this on tonight. I also put "T Tape" a thread sealant used for natural gas and gasoline on the bolts. I put a lot of it on. The inboard front bolt is suspect as it always seems to be wet.

    If this doesn't work, my next trials will be with Permatex form-a-gasket 1 and 2. I'll try the 2 first.

    Hopefully something works. This is more of a vent than anything else. I'll give an update to let people know if the Dow 55 or T Tape did anything positive.

    :huh
    #20