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  1. #1
    Saving the Manuals every day.. TheBlueMartin's Avatar
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    Runaway Engine! Went WOT with no lanyard!

    Of everything I've seen go wrong with SeaDoo's in the past 20 years, nothing confuses or scares me like this.
    I spend all day on the lake with my Challenger 1800, twin 782's. I pull it out in evening, start it up to clear the water out, rev it to 3000RPM. The starboard engine goes WOT, I throttle it down to 0 but it stays WOT, I pull the DESS lanyard, and the port engine dies but the starboard stays WOT until I flip the fuel switch off.
    I've seen throttle cables stick WOT on other machines, but pulling the lanyard always killed it. I have not even tried to start it again, but now I'm scared as hell this could happen when I'm on the water!

    Any ideas?? This is my second year with the boat, and I've never had an issue like this with it.


  2. #2
    Air leak in that motor or most likely that throttle cable freeplay is not adjusted correctly - to tight

    the motor glow plugged and ran away - Holding the throttle wide open or choking it out will shut it down - and yes it is very scary...

  3. #3
    Saving the Manuals every day.. TheBlueMartin's Avatar
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    That is logical, but what is going to cause the glow plug effect in both cylinders? There would have to be something that stays hot enough to cause ignition. The plugs themselves are clean and only have a few hours on them, and the RAVE valves only have a season on them since I cleaned and re-sealed them. I'll be taking the throttle cable off (since have never touched that one) and checking the play in it, then reseting it from zero. I just hope this doesnt happen again...

  4. #4
    SURFnTURF's Avatar
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    Your throttle cable has very little play in it or the low speed adjusters on the carbs are a little lean.Usually a 1/8 to 1/4 more open on the adjusters stops this.
    If it ever does it again the best way to stop it from free revving is leave the fuel on and hit the stop button and give it full throttle and this will pump fuel into the cylinders and stop this lean condition.
    The engine will stop instantly.

  5. #5
    Saving the Manuals every day.. TheBlueMartin's Avatar
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    I have the Prox air intakes on the carbs for two years now, but I backed both adjusters out 1/4 turn when I installed them and never had a problem. I do need to inspect the cables, howerver. I'll report back when I do.

  6. #6
    surferd15's Avatar
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    So your running flame arrestors and never rejetted your carbs?

  7. #7
    If i knew,...I wouldn't ask sea-one's Avatar
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    Definetly a "LEAN" runaway imo, you need to check those carbs for trash....take a reading on the plugs when you can and see whats going on there. Oh and if that happens again,Dont go into a shit panic, Pull the lanyard put in forward and go to FULL throttle and that should kill it......

  8. #8
    woodsrider40's Avatar
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    I pull the choke to flood the engine to kill it when that happened to me once.

  9. #9
    lextoy's Avatar
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    lean runaway, your carbs likely need to be cleaned, and really rejetted for the F/A's
    PS why are you running them after you pull out, just to blow residual water out?
    you dont need to flush, you are in fresh water lake right ?
    also do you have a choke knob on the dash to flood it out ? i dont know where they are on the boats,
    one for each engine ?? choke will flood and stop the engine every time.
    you ran it out of gas, so it started out lean runaway, and you leaned out out even more...
    the gas /oil mix in a 2 stroke is the only lubrication the engine gets, at WOT, you need all the lube you can get. also the right amount of fuel/oil helps to cool everything.
    lesson for others , be prepared for lean runaway on a 2 stroke, its not that uncommon.

    check your compression, hopefully everything is still fine.
    if you run lean a long time, eventually you score your cylinders, or you get lean siezure...
    and compression goes down.

  10. #10

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    I had that happen to me with a kawasaki jet ski. I called a friend and he said if it wasnt one of the things listed here, it's called "dieseling". It's caused by a leak in the gasket between the carbs & reed valve/rotary valve. Mine was an easy fix.

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