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  1. #1
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    Apr 2017
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    Lagrange GA
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    2002 250 PRO XB only turning 5000 rpms, NEED HELP!!!

    Boat sat 8 months with the lower unit messed up before I could get another one. Installed rebuilt torquemaster with the 1.25Ē shaft, took it out for test run and everything was fine. Went out a few more times, didnít run it wide open just run between 45 and 55 doing some fishing. Went to run wide open one day and it acted like it wanted to stop around 5000-5100 rpms, called a friend to ask him about it and he said letís take it out and see. Put it in and it ran fine, hit between 5900-6000 rpms speed around 74. So I thought maybe just a fluke, maybe bad gas or something I didnít know. Well it ran decent the next few trips but the other day I put in to fish tournament and it wouldnít turn over 5000 rpms and when you get to 5000 it drops down to 4900 and you lose around 1 mph.

    Checked gas for water, no visible water.
    Replaced plugs with champion QL77CC gapped at .35.
    Tightened all connections on batteries and cleaned connectors.
    I run 93 octane in it, poured some sea foam in the 16 gallons of fuel that was in tank.
    Took it out to see if it made a difference and no, reached 5000 rpms slowed just a tad and thatís all it will do. Checked to make sure nothing was behind hotfoot as well.
    Comes out of hole perfect, idles good and runs good all the way till it hits 5000 rpm.
    Prop stayed the same, lower unit I had on before had no problems. Boat would run 83 mph, turning 6000.
    It is a 2002 mercury pro xb 250, Trophy plus 26 pitch. Serial # is OT430081
    Im new to the forum, never posted anything on here so if Iím lacking info just let me know. Thanks


    Any ideas????
    Last edited by Chunk; 05-13-2019 at 07:10 PM. Reason: prop info

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  3. Major Flagelator Gamblinman's Avatar
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    Jun 2004
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    Yantis, TX
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    3,798
    #2
    Check your fuel pressure at all RPM levels to see if it drops.
    "Better to remain silent and be thought a fool than to speak out and remove all doubt."

  4. Member
    Join Date
    Apr 2017
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    Lagrange GA
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    #3
    10-4, would you happen to know what fuel pressure needs to be?

  5. Member
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    Apr 2017
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    Lagrange GA
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    #4
    Any answers?

  6. Member hookahawg's Avatar
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    Apr 2009
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    Montreal, Qc (Canada)
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    #5
    Don't know if it would contribute to your particular issue but I believe the plugs for that model year should be gapped at .040".
    Also, I wonder if you have some sort of fuel "restriction" showing up at the higher RPM's.
    I had that same engine and when I took my injectors to have them serviced, I couldn't believe the amount of fluid that spewed out of them at 6k RPM's during flow testing!
    Just my 2 cents, but I would suspect that any fuel starvation on that thirsty pig would be like trying to get on plane with power poles down...lol.
    I rebuilt my pulse fuel pump and took my whole fuel system apart and cleaned every bowl and screen as well as changed every fuel line in the boat to ethanol resistant.
    Motor ran like a beast after that.
    Good luck.
    2000 VIPER COBRA 201D /225 Merc EFI SER: 0T054298
    Where does the white go when the snow melts?

  7. Member Melton Jason's Avatar
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    May 2009
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    Knoxville TN
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    #6
    I had a similar issue with mine a few years ago and it was the stator. Not saying for sure that is the problem with yours but it fixed mine.
    Stroker DC21 Mercury 250 XB

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