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  1. #1
    Member
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    May 2017
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    Colorado
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    62

    2005 Mercury 125 ELPT0 Classic

    #1B040135

    Shut down on plane, have no spark from any coil.
    Have verified ignition grounds (continuity between terminal A at CDM and ground wiring bundle at ignition plate), stop circuit (BLK/YEL wire terminal B at CDM) has no continuity to ground with key on. Does have continuity key off or flipping kill switch.

    Terminal C trigger wire has a different voltage at each coil, .4-3.8 volts. That was with connector disconnected, I then backprobed wire and reconnected. Voltage goes to zero (at each coil trigger wire). Had a heck of a time making a good contact with my backprobers but am positive I am losing voltage. Also no voltage when cranking. The manual I have says I should be seeing .2-.5v during cranking. No info about what I should see voltage wise with connector off.

    Also ohm checked stator (believe I was on correct wires) and it was 722, spec 610-710


    Appears trigger coil is defective. Sound right with above testing? Anything else I need to check or recheck? If I do the trigger should I replace the stator while the flywheel is off? It’s the red stator. Don’t really want to spend more money but will if it’s what the pros do/recommend

    Thanks in advance for replying

  2. Member
    Join Date
    Jun 2013
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    LONGVIEW TEXAS
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    #2
    ohm test trigger, shouldnt need stator too , another test unplug each cdm one at a time to see if spark returns, start with #3 short there will kill all 4
    .................................................. ...the scariest thing in life is the unknown ...................................

  3. Member
    Join Date
    May 2017
    Location
    Colorado
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    62
    #3
    Installed genuine Merc trigger, still no spark…Was frustrated so did not recheck anything but per Merc manual troubleshooting, the stop circuit is functioning and stator ohms in spec when originally checked. Will recheck tomorrow after work.

    Have disconnected all CDMs one at a time, still
    no spark on any cylinder.

    With the 2+2 system on this engine, do the lower carbs with no idle circuits fire during cranking? Would think they’d have to but it wouldn’t be the first time I’d be wrong about this pig motor. I’m at a loss. When I had flywheel off and oil tank pulled back all wiring looked ok visually. Never had an issue in 5 years of owning until it just died. Hasn’t even farted since.

  4. Member
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    Jun 2013
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    #4
    when choke is engaged bottom 2 are working cyls
    .................................................. ...the scariest thing in life is the unknown ...................................

  5. Member
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    May 2017
    Location
    Colorado
    Posts
    62
    #5
    dug into wiring and found two voltage regulator wires melted together, separated them and spark has returned. Could not see them visually until I pulled harness out a bit. Will replace regulator and connectors. One wire is blk/yel, assume it has something to do with kill circuit? Will look at wiring diagram closer, would like to understand the circuit completely.

    Thx for your replies Joe54

  6. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
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    13,941
    #6
    blk yellow was problem , be sure reg is good , likely not though
    .................................................. ...the scariest thing in life is the unknown ...................................