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  1. #1
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    Jul 2013
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    Engine fouling Plugs-2019 250 Pro XS

    SN 2B573392. About a year ago at 70 hours I fouled plug for cylinder 6 badly. Dealer said plug wires on recall and replaced wires and all plugs. Fast forward a year with 90 hours and I had another issue with roughness. Took in and plug for cylinder 7 fouled. Replaced all plugs again. Boat is out about every 3 weeks and I have just a couple of short idle zones on lake. Rarely run over 5000 rpms. No faults or codes. I am concerned over what would be causing this issue and how I can keep from replacing again in a year when out of warranty. I use the cocktail. Could it be the deteioration of the fuel since I only run 3 gallons out each use but add new fuel periodically. Fuel is 87 octane with ethanol. And ideas? Thanks.

  2. Member
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    Aug 2022
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    Pompano Beach,FL
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    #2
    run it wot every trip for a few mins.

  3. Member
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    Jul 2013
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    Indianapolis Indiana
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    #3
    Ok. Thanks

  4. Member
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    Apr 2014
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    SW, Ohio
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    #4
    using carbon guard in fuel?
    2022 z519 cup 225 merc 4s ser # 3B210484. 2--hds12 live units. 2 poles, atlas plate, ghost, hamby's, active target, merc digital gauges
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  5. Member
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    Apr 2009
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    Luling, La.
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    13,351
    #5
    My 2020 engine went 300 hours on a set of plugs. My engine smokes some on Start up, whether I leave it level or trimmed. A few of the plugs looked like they were just about to be fouled. I hope I get 300 hours out of this new set....fuel additives may help with carbon build up, but I doubt they help a lot with engine oil being burned by plugs..

  6. Member
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    May 2011
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    Spangle, WA
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    #6
    Quote Originally Posted by mactlman View Post
    using carbon guard in fuel?
    Not necessary if he's running Don's recommended cocktail.

    Would be interesting to see run time history on his engine.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  7. Member
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    Jul 2013
    Location
    Indianapolis Indiana
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    634
    #7
    I am sure dealer had the rum time history but never mentioned it. Just said to run engine harder since V8’s need to be run hard.

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    Greenville, SC (US)
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    #8
    Quote Originally Posted by mactlman View Post
    using carbon guard in fuel?
    Quickare and Quickleen are the recommendations.


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