Thread: RPM issues

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  1. 05-25-2015, 08:10 AM #1
    mjcarder
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    RPM issues

    Have a 1998 203 Champ with 1998 225 optimax. Can not get over 5000rpm. Motor checked out fine. Tried multiple props including a 21, 23, 24, 25 pitch with no success. Motor rated at 5650rpm. Any suggestions will be appreciated.
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  2. R Warner
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    #2 05-25-2015, 08:18 AM
    Are you sure your rpm gauge is working properly?
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  3. mjcarder
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    #3 05-25-2015, 08:31 AM
    No. Is there a way to test gauge? Even if it is not, I would think we should be more mph. All I am getting is 51mph.
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  4. pmgoffjr
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    #4 05-25-2015, 08:42 AM
    If you changed props and saw no difference you have motor issues. Find a new tech.
    Pat Goff

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  5. scotty34
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    #5 05-25-2015, 12:32 PM
    Quote Originally Posted by pmgoffjr View Post
    If you changed props and saw no difference you have motor issues. Find a new tech.

    X2
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  6. Lea
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    #6 05-25-2015, 01:21 PM
    X3!!! Something is going on with that motor. It appears to be from the time frame where the larger displacement Optis had issues. Talk with the folks here on BBC in the Merc Motors forum. Give Don your motor serial number.
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  7. 02champ
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    #7 05-26-2015, 04:24 PM
    I bet it is missing on a cylinder or two... Just about the only way it would turn 5 but not 5600.. Injector stuck or coil not firing.
    George Hoehne- Moscow Mills, Mo-

    Champs Owned- 1979 -176 / 1990- 201 / 2002-196, current 1994 -190
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  8. 02champ
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    #8 05-26-2015, 04:26 PM
    Or fuel issues like a bad bulb, or fuel pressure. FUEL, Air, Spark, Compression is all you need. Start with one and go through them, you will find something.
    George Hoehne- Moscow Mills, Mo-

    Champs Owned- 1979 -176 / 1990- 201 / 2002-196, current 1994 -190
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  9. Gtolson89
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    #9 03-12-2023, 07:50 AM
    Ever figure this out? I’m having a similar issue with my 150
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  10. STLBassBuster
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    #10 03-12-2023, 04:47 PM
    Quote Originally Posted by Gtolson89 View Post
    Ever figure this out? I’m having a similar issue with my 150
    150 opti? I would make sure all your coils are working. They are notorious for failing. If that's not it, I would go through the fuel system next and check spark plugs (confirm proper gap).
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  11. Tx Champ
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    #11 03-12-2023, 05:56 PM
    Quote Originally Posted by Gtolson89 View Post
    Ever figure this out? I’m having a similar issue with my 150
    The Author hasn't been on BBC since 5-31-2015. It's really best to take this to the Mercury forum --> Mercury Motors (bbcboards.net)
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