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Thread: 912ULS ignition problem

  1. #11
    Senior Member Slyfox's Avatar
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    Dec 2008
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    felts field, spokane
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    Default Re: 912ULS ignition problem

    good thought. I found my problem because once it wouldn't start at all. after that happened it started every time. I pushed to find something wrong. Now, I also start my plane with the headsets off and pay close attention to startup and run. I noticed that my plane was starting up but had a different sound after start up. well after not starting at all just cranking I decided to do a mag check right after startup, that's when I found that one module was not firing. after a few second, more than likely after it reached a good rpm like 2000 the offending module started working. At that same time that the module started working of course the engine sounded much better. another good test is to go to one side and than the other when at operating rpm, in other words, do a mag check in flight.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  2. #12
    Senior Member Dave S's Avatar
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    Oct 2008
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    St Paul, MN
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    1,833

    Default Re: 912ULS ignition problem

    Update on the ignition problem

    Following some extensive diagnostic work and great ideas from many of you on the list, I called up the Lockwood tech folks who confirmed the issue was what they call a "cut in" problem - i.e. normal cranking speed will not result in a spark on a bad module. Likely one of the modules had been bad for a while so when the second one went bad it only appeared to be a double fail with no spark at cranking speed on either side. - With one good and one bad the engine starts on one then the second one starts working when the engine is up to idle speed - so a runup/mag check will never catch this.

    Anyway, decided to get two new modules of the "soft start" design and the little harness to make that work. With the new parts the engine starts normally and runs like it should.

    30+ knot surface winds today so had to suffice with a ground run til that settles down.

    An interesting comment from Lockwood - apparently either warming up a bad module OR cooling it will cause it to work - so I tried icing the modules one morning - sure enough that worked too - I still claim semiconductors are all voodoo

    Thanks to all who submitted ideas on this
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  3. #13
    Senior Member
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    Dec 2017
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    Mapleton,UT
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    1,224

    Default Re: 912ULS ignition problem

    Good job fixing this and thank you for posting what you found. I am sure this thread will help someone down the road!
    Dustin Dickerson

    Building 7ss STI x 2
    Oratex
    29" shock monster
    EP912STI 155hp
    Garmin
    N33TF......FLYING!
    N53TF......FLYING!

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