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  1. #1
    Member
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    Jul 2017
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    symptoms of bad coil

    could a bad coil cause a rough idle and sight miss fire in neutral and right off neutral at trolling speeds? runs great above 800 rpm

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    #2
    Please see the Forum Announcements, and provide the REQUIRED info each time you post.

    Very unlikely that a coil ONLY malfunctions at idle. Not impossible, but VERY unlikely.

    Now a plug wire... spark plug, those are certainly more plausible.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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  3. Member
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    Jul 2017
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    #3
    Gotchya tested coil wires with timing light at various rpms no issues found

  4. Member berudd's Avatar
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    Apr 2013
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    Morrisville, NC
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    7,069
    #4
    Mine idled poorly but also lost top end. It also made enough spark to fire a timing light so it told be all was well when it was not.
    Bruce
    2019 20 TRX Patriot
    Mercury 250 ProXS Fourstroke
    HDS 12 Live - Console
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  5. Member
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    Jul 2017
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    IL
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    97
    #5
    Mine runs great up top.