Results 1 to 9 of 9

Thread: Detonation???

  1. #1
    Ramps's Avatar
    Join Date
    Jan 2008
    Location
    Myakka, FL
    Posts
    651
    +1
    28

    Question Detonation???

    O.K. I went to the intercoastal for some good times and noticed my engine over heat light sensor come on. I got back to ramp and put ski on trailer. I then proceeded to start it just to get any seeweed and stuff out. Well holy sh#@ my engine would not stop I pulled lanyard, plugs still revving like a monster. It started smoking and my thought was it got so hot it was detonating so I quickly grabbed my fuel line up at the front of the ski and pinched it off and about 30 seconds later it shut off. I was freaked out to say the least. When I got home I realized the inlet hose at the third cylinder had torn, I fixed that and then flushed it with no warning lights coming on. I need some advice, of course I will do all the regular checks such as comp test etc...Also, I noticed when I was coming into the ramp my idle went way down until I gave it just enough throttle to get it on the trailer...I think it would have shut down If not given any throttle...I think I was very lucky this deto did not happen when I was coming up to the ramp??? I need some advice!!!!


  2. #2
    Ramps's Avatar
    Join Date
    Jan 2008
    Location
    Myakka, FL
    Posts
    651
    +1
    28

    Question Help......

    Check comp 140,145,147. I think I shut it down on time as for the cause I believe it was due to me turning my pro series jetworks valve in to far and was not getting any water in.

  3. #3
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    Location
    United States
    Posts
    11,875
    +1
    30
    What you are describing is a lean runaway if you pulled the throttle wide open it would have stopped the motor. Check for air leaks.

  4. #4
    Ramps's Avatar
    Join Date
    Jan 2008
    Location
    Myakka, FL
    Posts
    651
    +1
    28

    Exclamation Lean Runaway..

    Quote Originally Posted by OsideBill View Post
    What you are describing is a lean runaway if you pulled the throttle wide open it would have stopped the motor. Check for air leaks.
    So I should check all hoses especially exhaust and turn out my highs a little more on the carbs? My lows are at 1 1/8.

  5. #5
    philip_gpr's Avatar
    Join Date
    Dec 2005
    Location
    Canada
    Posts
    2,724
    +1
    3
    jetworks valve in to far and was not getting any water in.

    This just means the waterbox wasn't getting as much (or any) water. Ski would be noisy and maybe you would melt the rear exhaust hoses. It won't cause the ski to runaway like you described.

    Check for air leaks.

    this means either one of your gaskets on the carb side is leaking or the cases or crank seals are leaking

    the air leak is causing the air fuel mixture to be too lean (in essence it is changing your jetting to something leaner than you want)

    this is serious because if will lead to engine failure, but it is also a nuisance to try and fix - motor should come out and be pressure tested, unless you can find a leaking carb gasket (which will be tough to determine)

    If anybody has any further ideas on trouble shooting this please speak up.

  6. #6
    philip_gpr's Avatar
    Join Date
    Dec 2005
    Location
    Canada
    Posts
    2,724
    +1
    3
    I realized the inlet hose at the third cylinder had torn

    Anybody, is there any chance this lack of water to cylinder 3, which did cause the motor to overheat also caused the motor to runaway?????

  7. #7
    Ramps's Avatar
    Join Date
    Jan 2008
    Location
    Myakka, FL
    Posts
    651
    +1
    28

    Exclamation Inlet Hose...

    Quote Originally Posted by philip_gpr View Post
    I realized the inlet hose at the third cylinder had torn

    Anybody, is there any chance this lack of water to cylinder 3, which did cause the motor to overheat also caused the motor to runaway?????
    First off thank you Philip, I can only hope it will be this simple...Chime in Gurus...

  8. #8
    Tyrael's Avatar
    Join Date
    Oct 2007
    Location
    Cairns, QLD, Australia
    Posts
    76
    I'm with philip_gpr, check for air leaks. Also check your PV covers for leaks.
    Its freaky when these things happen isn't it... I heard of one guy removing his spark-plug leads and it was still running!

  9. #9
    Ramps's Avatar
    Join Date
    Jan 2008
    Location
    Myakka, FL
    Posts
    651
    +1
    28

    Lean Runaway..

    Hey All,

    Just wanted to give an update. Went out yesterday after checking all the basics have not checked for air leaks and have not went through the carbs yet.
    On take off from idle it almost falls on its nose, then picks right up and pulls through the full RPM band. This makes me think that Philip was right air leak or carbs. I am thinking it is the carbs just because of the way it feels and when it happens.
    The lean runnaway happened on the trailer after I was done and I just grabbed the throttle (WOT) and choked it out. Stalled almost immediately...Thanks you guys, I guess its back to the bench...

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. The mystery of detonation
    By J-ME in forum Yamaha How To & FAQs
    Replies: 2
    Last Post: 04-06-2007, 11:34 PM
  2. RPMs vs Detonation Question
    By Mr Bill in forum Yamaha PWC Performance (2-stroke)
    Replies: 10
    Last Post: 09-21-2006, 08:00 PM
  3. detonation question
    By andy95'slx780 in forum Polaris Open Discussion
    Replies: 1
    Last Post: 09-15-2006, 10:02 AM
  4. Detonation, Ignition, Lean condition?
    By Smitty in forum Yamaha PWC Performance (2-stroke)
    Replies: 18
    Last Post: 06-21-2006, 11:57 PM
  5. Definition of Pre - Detonation (ABNORMAL COMBUSTION)
    By RX951 in forum Yamaha How To & FAQs
    Replies: 1
    Last Post: 05-21-2006, 04:16 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •