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no start

in General Tech Discussion 9 years ago
I tried to start my 2004 rotax 912uls yesterday and it would not. I have had difficulties in the past but after a change in gap on the plugs I have had no problems. It has started all winter whenever I asked it to and now it will not. I have never had a no start. Further investigation today proved that i have an ignition problem. Fuel is getting to the carb, pressure comes up while cranking (emptied the bowls and they refilled). I pulled a plug(Looked good) and could not detect a spark.
How does one check the ignition modules to be sure before replacing. Apparently a costly part. I would like to confirm before replacement.
Please advise

  • Re: no start

    by » 9 years ago

    How good is your battery ?

    Thats the first thing that comes to mind after reading your post, it needs to spin your engine 200rpm in order to get the ignitions to produce.
      
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  • Re: no start

    by » 9 years ago

    No problem there. New battery last year, good cranking. even after many tries, it did not slow down.
    i want to test the ignition modules but not sure how.
      
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  • Re: no start

    by » 9 years ago

    Hi Tim,

    You can't test the modules. If you live in the US you can send them to Lockwood and they can test them.

    Even though you think your battery is good either use a different battery or jump it. You need approximately 92 rpm at the prop to fire and if it's down a few rpm it won't fire and your ear can not tell the difference. A good battery should turn the prop well past that 92 rpm. This needs to be ruled out as a cause. I have seen a hundred people swear something else was wrong or the modules were bad and waited until they were frustrated at an end and jumped the battery and it started. A good diagnostician never leaves any stone unturned and follows a logical order that usually starts at the most common cause and the least expensive cause.
    You may have had a module starting circuit go out awhile back and you didn't notice and now the other has failed.
    Try this little trick. It's cheap and easy. Put some ice in a one gallon zip lock bag and place it around the two ignition modules for 30 minutes and chill them down. If it starts after that then replace the modules.

    If the first two things don't work it's time to take a good hard look at the wires coming off the ignition modules and make sure they have not contacted the crankcase or other part and worn through the insulation. Look at these wires closely because a bare wire or a broken one can hide sometimes. I would especially pay attention to the red wires and the white ground wires. Also look at the back of your ignition switches and tighten all wires on the back even if they look tight put a screwdriver or wrench on them.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: no start

    by » 9 years ago

    Thanks, I like your logic.
    I will let you know the outcome.
      
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  • Re: no start

    by » 9 years ago

    Just had another no start today and I had him try the ice. Do 30 min of ice instead of 15 min. Started right up. Give this a try.

    Copy and pasted from another site:

    "My starting problem back, will not start pulled plugs several are wet, yesterday started
    as soon as i turned key, today nothing, replaced with new plugs no start it tries but
    same problem some new plugs wet pulled out the 4 on top and grounded them to
    engine number 1 and 2 on top will not fire 3 and 4 on top look good didn't check
    any on bottom figured was no need i have a problem.??SUGGESTIONS I guess
    I will switch boxes and see what that does first."

    "!5 min. of ice bag all plugs started to fire plane started right up, guess I will
    be spending big bucks on new soft start modules thanks Roger for advice."

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report
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