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Thread: XB9S – running very roughly – tried various fixes – need some expert help!

  1. #1
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    XB9S – running very roughly – tried various fixes – need some expert help!

    2003 XB9S BUECB “Factory Race ECU” and Factory Race exhaust.
    Low miles and well looked after and not messed with - just stock. Was running fine before.
    After not riding it for a couple of months when I tried to start it - 20 seconds of churning, then started and ran very roughly and after 10 seconds revs dropped until engine stopped. Same each time I try and runs so badly (cuts out and splutters) than unrideable.
    ECMDroid/Buelltooth – shows no error codes.
    First I suspected earths. Cleaned all (battery, ecu, frame dogbone and coil back to bare metal and checked with meter – all OK. Then added additional earth cables battery earth to ECU earth, frame dogbone to battery – and coil to battery -. Problem still same.
    Fitted new plugs, cleaned air filter – still same.
    Fitted new intake seals last year and did leak check again and no leaks.
    The AFV value is showing as 147 so if I understand correctly the ECU is receiving info from somewhere that the bike is running lean and is adding more fuel?
    So suspected O2 sensor. Used the excellent instructions on Buelltooth to disable O2 sensor, manually set AFV to c100 etc and if anything it ran worse – so seems not the O2 sensor. Then burned back to orig ECU settings.
    It is firing on both cylinders and fuel pump runs.
    Reading the Forum – a fuel supply issue is a possible cause – but before I spend $ and spend hours pulling it apart – Any way to test this without the special HD tool the workshop manual refers to?
    And any other things I should be looking at that I can test with ECMdroid and normal workshop tools?
    Your help much appreciated and when I fix it I will explain what it was so that others can benefit.
    Thanks
    Paul
    Midhurst, West Sussex, England.

  2. #2
    Senior Member rchuff's Avatar
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    You can put a fuel pressure gauge on fuel line and see where it is at. It should be around 48 to 50 psi anything less means you need a fuel pump. That's the only way you will know where your pressure is at.

  3. #3
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    Could the fuel have gone bad ?

    I just noticed, after reading this again that your in England, do they put ethanol in the fuel there ?
    I would start with the battery since you didn't mention above, it could have gone bad while in storage, get it load tested.
    Last edited by njloco; 02-28-2019 at 12:39 PM.

  4. #4
    Senior Member jl551c's Avatar
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    A friend of mine's Fatboy was running the way you described your bike is running. I recommended pouring some Seafoam into his tank and it cured it pretty quick. It's a long shot but it can't hurt.

  5. #5
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    Seafoam for the win.

  6. #6
    Senior Member Chicknstripn's Avatar
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    Have you tried resetting the TPS(Throttle position sensor)?
    I’d give that a shot before anything else.

  7. #7
    does it make a nice strong "normal" fuel priming sound when you first start it?

    Have you checked the plugs?

  8. #8
    Senior Member Cooter's Avatar
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    It hasn't run long enough to even use the O2 sensor for closed loop operation.

    Stick with the basics. Pull those fouled plugs out and replace them or clean them and dry very well.

    No telling if the AFV at 147 is because the old gas/ sat for a long time, but the ECM is trying to put 147% more fuel in for a reason. I would look for an intake leak. are the intake seals good? did you have the airbox base off?

  9. #9
    Senior Member BuellyBagger's Avatar
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    check spark (plugs might be fouled again like cooter said with the rich condition, ohm test your wires, check for spark at the coil)compression(while you;ve got the plugs out check compression just for safety sake, you didnt say how many miles are on this motor) air (test seals again, check if the velocity stack is seated right, and reset the TPS CORRECTLY) and fuel (fresh fuel, listen to the pump, and run a fuel pressure check).

    air, fuel, spark, and compression...
    Last edited by BuellyBagger; 02-28-2019 at 11:32 AM.

  10. #10
    Senior Member Silverrider's Avatar
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    Quote Originally Posted by Outlaw View Post
    Seafoam for the win.
    Seafoam has been Rebranded to Teafoam due to volume of usage.



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