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912 ULS - does not start when cold

in 912 / 914 Technical Questions 11 years ago
Hi,
I have a Sport Cruiser LSA, bought new from the CZAW factory in NOVEMBER, 2007 equipped with the Rotax 912 ULS. The engine has now 610 hours and it has been working faultless since new. After the last routine maintenance at 600h, the engine does not start when cold. I have every time to warm the 2 Ducati ignition modules with a hair dryer for about 5 minutes and then it starts immediately.
I've been told that this problem is not new and it can be caused by a faulty modules which unable the engine to start when cold.
After running the engine for a short period of time it starts again without any problem as it always did before.
Any suggestion to solve the problem.
Thanks in advance for you help.
Manuel

  • Re: 912 ULS - does not start when cold

    by » 11 years ago

    Hi Manuel,

    Sounds like you may need new ignition modules since they are fine after you warm them and after they have started a during the day.

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

      
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  • Re: 912 ULS - does not start when cold

    by » 11 years ago

    Thanks Roger.
    As the engine gets started and works faultless during all day flight, after 5 minutes of having warmed up the ignition modules, I was assuming that the modules were OK.
    Can you pls explain me why do you think that I might have to replace my 2 ignition modules?
    Why do they start the engine after being warmed for 5 minutes or less?
    This problem is happening in this time of the year - this summer in Portugal, during day time, the temperature has been usualy above 20° Celsius - which can not be considered as a "very cold" start :)!
      
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  • Re: 912 ULS - does not start when cold

    by » 11 years ago

    Manuel,

    This exact same problem happened to me. I thought for a while it was carb problems. Finally I sent my modules off to Lockwook Supply and had them checked. Both failed, requiring as much as 40 seconds and 1200 rpm or so before they began to fire. It seems that one module began to fail first but, since one worked fine, the engine would start just fine. When the other began to fail it was difficult to start. My engine is only a year older than yours and this problem started when I had less than 500 hours on it.

    Rotax says there is no problem but Lockwood has noticed that engines built around this time were equiped with modules that would sometimes fail in this way. You can buy a pair of new modules with the "soft start" built in for about the same price as one of the old style modules. The new modules will not fail in the same way. Time will tell. You can also buy the old modules, but they cost about $1000 each. Let me see......$1000 for two new style or $2000 for two old style.

    I went with the new style modules. You will have to hook up one more wire, a really easy install.

    By the way, after a while my old modules began to be hard to start later in the same day, after having been run for awhile and were warm. I recommend getting the new modules as soon as you can.

    Alan
      
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  • Re: 912 ULS - does not start when cold

    by » 11 years ago

    Quoted from another source with a copy and paste:

    "A little technical detail to start with. The failure you are describing on the ignition modules is called
    “cut-in”. This means that the ignition won’t cut in and start sparking at 250 rpm like it should, and doesn't start running until some higher rpm. Once it does start running, it will continue to run – even when shut down and started again – for the rest of the day. When they’re left setting for a period, they go back in the cut-in failure mode again. This is why – once the engine is started – the problem never shows up on the mag check. As a result, we have never had the experience of these failing in this mode in the air. It’s always on startup."


    It sure sounds like new modules are in your future. You can send them in for testing.

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

      
    Report

  • Re: 912 ULS - does not start when cold

    by » 11 years ago

    Hi Alan and Roger,
    Thank you both for your information.
    So, as you both mentioned, it looks clear now that I have to go for new ignition modules and it seems that I should buy the new 'soft start' built in modules.
    Can you pls inform me 1) to whom should I place the order for the 'soft start' built in modules and 2) where can I look for the new wiring connexions for installing the new style modules?
    Thanks and best regards,
    Manuel
      
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