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  1. 10-03-2021, 02:44 PM #1
    rudapa
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    3 hours on the 250 - spitting and sputtering??

    <3B101468>

    Doing my 2 hours of break in on my new 250 Pro XS 4-stroke at about the 45 minute mark it starting running really rough at lower RPMs. If I goosed it up past 3500 RPMs it seemed to smooth out. Most of the time at idle in gear or up to 2K RPMs it now spits and sputters. It never stalls. Now that I'm passed 2 hours I was able to try to open it up. It runs 65 MPH at 5600 RPMs with the throttle buried. Seems smooth if over 3500 RPMs but goes back to spitting and suttering when at low RPMs in gear. Neutral it is smooth "most" of the time. On the RPMs I guess I may need a 23 pitch? She isn't heavily loaded. Boat handles really well just like my 721, but the Merc is unhappy at low RPMs.

    921 Elite - 24 Fury - Atlas plate is 4" on the ruler (15 on the gauge). I'm trimmed to 8.5 when "running it".

    Any idea what causes this? I'm going to take it in obviously but curious in the interim.
    Last edited by EuropeanAM; 10-04-2021 at 04:08 PM.
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  2. EL Skeeter
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    #2 10-03-2021, 07:03 PM
    Before Don Weed tells you post your serial number.

    Sticky: Please Review the Forum Announcements BEFORE Posting and follow. Thanks!

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  3. rudapa
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    #3 10-03-2021, 07:35 PM
    Oops!! 3B101468
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  4. thommo59
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    #4 10-03-2021, 07:40 PM
    Sorry wrong post
    Last edited by thommo59; 10-03-2021 at 09:18 PM. Reason: Mistake
    2018 TRX 18. 2020 Mercury 200 Pro XS V8
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  5. rudapa
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    #5 10-03-2021, 07:52 PM
    My battery has been charging as expected so far. My issue is low rpm rough running, shaking and sputtering.
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  6. mikesxpress
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    #6 10-04-2021, 07:22 AM
    Get it back to the shop and reparations done to correct your sputtering issue before concerning yourself with prop selection. You don't know what your missing if it's not running correctly.
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  7. SilverFox579
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    #7 10-04-2021, 07:47 AM
    ^^^^+1^^^^
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  8. EuropeanAM
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    #8 10-04-2021, 04:10 PM
    ^^^^^^^ +2 ^^^^^^^^^^

    Plugs, Wires/Wire Connections, Injector Connectors properly seated on injectors (visually inspect for any pinched wires, wiggle-test while running, etc)- Starboard-side first.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  9. rudapa
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    #9 10-04-2021, 06:39 PM
    #8 plug wire wasn’t connected. Will see tomorrow but I’d bet that fixes it. Wonder why it didn’t throw a warning? Thanks
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  10. MichaelJ3
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    #10 10-04-2021, 07:21 PM
    Quote Originally Posted by rudapa View Post
    #8 plug wire wasn’t connected. Will see tomorrow but I’d bet that fixes it. Wonder why it didn’t throw a warning? Thanks
    My guess is the misfire was logged in the history, but lots of ECU's require a fairly large number of mis-fires in some unit time to actually throw a code (Check Engine Light in a car, warning horn/message on your outboard). Not sure about this one, but Don will know.

    Hope you are good to go now...
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  11. bottomfisher
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    #11 10-04-2021, 10:51 PM
    I struggled with a “miss” at idle, weird holeshot issues, and erratic running at cruising RPM 3500-3800 depending on prop for a while. Brought it in to shop and they found nothing, but they didn’t test it under load just at idle at the shop. Freeze frame and fault history showed nothing. Got it home just knowing something had to be overlooked - pulled the cover off and started inspecting plugs/wires and found #1 plug wire floating about a 1/2” or so off. Brought back to the shop to show them and they ordered me a new plug wire because it was booger’d up from arcing off. Once replaced, and fully seated, all “miss” issues were solved. As I said, nothing showed up in the fault/freeze frame history.
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  12. rudapa
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    #12 10-05-2021, 01:54 PM
    Mine ran good with no issues now that it has 8 plug wires. 6300 RPMs and 72.5
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  13. 21xTriton05
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    #13 10-12-2021, 09:50 AM
    Quote Originally Posted by rudapa View Post
    Mine ran good with no issues now that it has 8 plug wires. 6300 RPMs and 72.5
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  14. rudapa
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    #14 10-12-2021, 12:04 PM
    I think I read the 6300 wrong - she is giving me 5900+ and hitting 72+ consistantly now that I'm paying good attention.
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