KTM 790 takes a few tries to start

Discussion in 'Parallel World (790/890)' started by doctorblanco, Sep 10, 2019.

  1. Beshar

    Beshar Adventurer

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    I don’t think that matters. The ecu just “listens” for that initial press.
    #61
  2. Tool.Nerd

    Tool.Nerd An idiot that owns a bike

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    Quick press with indeed finger, no touching throttle. It turns over on its own and fires up quickly. Then the rpms fall immediately down and it dies.
    #62
  3. Motopumps

    Motopumps Long timer Super Supporter

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    Are any of you new posters reading the thread from the start or just posting???
    #63
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  4. Some_Dude

    Some_Dude Been here awhile

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    When I first got the bike I’d turn the key on and hold down the starter until it fired. It fairly consistently took three tries to start.

    When I clued into it being fuel injected I started tapping the starter and it fairly consistently took two tries to start.

    When I noticed the fuel pump would run for a second or two after turning the power and ignition on and I started giving it time to prime the fuel line it fairly consistently took one try to start.

    Sometimes it still takes two times to start, but I’m also getting single starts at temperatures down to -4. I think the hard starting in the morning has less to do with temperature and more to do with fuel delivery, particularly if the pump has no time to prime before ignition.
    #64
  5. Tool.Nerd

    Tool.Nerd An idiot that owns a bike

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    Been watching/reading this thread since the first post, thank you.
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  6. Thumper Dumper

    Thumper Dumper Been here awhile

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    I've had it start first time and after four attempts on the same tank of fuel. Our fuel is generally good quality and 95 octane.

    Tried all the different starting techniques, quick push, waiting for 30 sec before starting, starting as soon as the dash lights up etc. etc.
    I've even had the bike start up first time in the morning and then ten hours later when leaving work it needed a few tries.
    Mine started soon after I got the bike and the only thing I could think is I bought the bike at a higher altitude and I live at sea level but I'm pretty sure the ECU should compensate for the difference in altitude.
    Later this week I will disconnect the Booster Plug and see if the issue has returned, will report back.
    #66
  7. yokesman

    yokesman Long timer

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    I dont have a 790, but do you wait for the pump to ramp up or just do it?
    #67
  8. Thumper Dumper

    Thumper Dumper Been here awhile

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    I always wait for the pump, have tested a few different methods but none worked consistently.
    This is why I believe its due to the lean idle (Euro 5) as soon as I fitted the booster plug the problem went away and all it does is make the mixture a bit richer.
    It has no bearing on the fuel pump, how the start button is pressed etc.
    Just for the sake of giving all the details I have removed the catalytic converter but the problem started before it was removed.
    #68
  9. Beshar

    Beshar Adventurer

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    I think it’s a combo of lean mixture and fuel quality.
    #69
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  10. ShaftEd

    ShaftEd Long timer

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    I’ve done 5 stone cold starts since installing the Booster Plug and all were first start. At this point I’m going to say the BP solves the multi start issue.
    #70
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  11. Motopumps

    Motopumps Long timer Super Supporter

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    I installed the Booster Plug I had for my 1290 SA last night. (I removed it when I put on Rotteweiler fueling dongles)

    Two starts, worked first time for each. Rode to work this morning. Smoother low RPM partial throttle drivability. Bike pulls better from low RPM in upper gears. Will see how much this affects MPG. Definitely a noticeable difference.

    Rob
    #71
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  12. RWJorg

    RWJorg Adventurer

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    Installed the booster plug the other day. At first I was a little disappointed; when I went to start it, same ol crap - it died quickly. Started it up again and let it run for a bit. Let it sit for another 8 hours or so and checked it the next morning. Fired right up, idle sounds wayyyy better, not like it's choking and revving up and down. Holds steady. Two more tests with another 10+ hours between and same results.

    Will get out and ride it this weekend to test throttle response, but so far loving it.
    #72
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  13. braaap!

    braaap! Long timer Supporter

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    All these poor / intermittent start issues are intriguing... I’ve never, ever had a false start from day 1, hot, cold... not one. Mine has started every time after TFT has done it’s ‘ready’ cycle, fuel pump actuation...
    Have a BP now to install and evaluate the idle characteristics and fuel economy, just for shits and giggles.

    Maybe our air is thicker down here?..
    #73
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  14. Motopumps

    Motopumps Long timer Super Supporter

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    Where is down here?
    #74
  15. spartanman

    spartanman regret minimizer

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    Yes, please tell us about the mileage hit.
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  16. kzeb

    kzeb Been here quite some time

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    Ask Men At Work and they might give you the answer with a smile and a vegemite sandwich mate :lol3
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    Buggar had to edit my poor spelling :fpalm
    #76
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  17. braaap!

    braaap! Long timer Supporter

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    Cheers Mate! :)
    #77
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  18. RWJorg

    RWJorg Adventurer

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    went to visit a lady friend in NZ, she feeds her kids that Marmite crap. BARF
    #78
  19. SEK_Nick

    SEK_Nick Been here awhile

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    I am also very curious what yhe booster plug does to fuel economy. I have beem very much enjoying 54 to 58mpg!
    #79
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  20. TrailTrauma

    TrailTrauma Nemophilist

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    One of my favourite bands in HS. Saw Collin Hay live here in a small bar yrs ago.

    //

    My bike, too, used to take 2 or 3 tries until I started doing 2 things, one smart and one dumb. First I changed from a hold to a tap on the red button, and second I blip the throttle quickly a second later. haha. Works like a charm...
    #80