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  1. #1
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    Stator/ Regulator problem

    Have a 2002 90 ELPTO #OT481094. Starts fine, sometimes the tach will bounce around erratically while running. Going down the lake the RPM's will drop for a couple seconds, then pick back up. Doesn't seem to be missing, just a RPM drop and picks back up. What should I look at 1st.

    Thanks

  2. Electrical/Wiring/Trolling Motors Moderator CatFan's Avatar
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    #2
    Is the engine actually changing speed or just the tach?
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  3. Member
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    #3
    Quote Originally Posted by CatFan View Post
    Is the engine actually changing speed or just the tach?
    The boat will slow a bit, the RPM will randomly move up or down.

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Check the voltage regulator for burnt, browned, blackened or "crispy" wiring and connectors (especially the RED and YELLOW wires).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 46 years (learn something new every day).
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  5. Member
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    #5
    Quote Originally Posted by EuropeanAM View Post
    Check the voltage regulator for burnt, browned, blackened or "crispy" wiring and connectors (especially the RED and YELLOW wires).
    They look fine. One thing I have noticed is that my starting battery takes a couple of hours to charge after I get home. It's only 4 months old.
    Last edited by Hydrasport80; 11-16-2021 at 02:02 PM.

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Clean cannon plug connector (disconnect, clean male pins, spread male pins SLIGHTLY, then reconnect and lock in place with factory supplied keeper).

    If problem persists, Isolate the tachometer (disconnect and isolate wiring)- see if the problem persists.

    And if still occurring, temporarily (for one very short run to diagnose) isolate the regulator as well.

    NOTE: "ISOLATE" meaning to "Disconnect and prevent connectors from touching other objects by means of an insulating material such as plastic, rubber, or electrical tape".


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 46 years (learn something new every day).
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  7. Member
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    #7
    Found a new Mercury OEM regulator on Ebay for $35 shipped. Most were listed between $220 to $169, appears the guy didn't know what he had. In the meantime, I'll check all the connections as suggested.

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8
    Very unlikely that's OEM... but hope it works out well for you.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 46 years (learn something new every day).
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    #9
    Put the new regulator on and took it out today. The new regulator didn't help, same as before. Next step will be to isolate the tach as mentioned above. What is the reasoning behind doing this.

    Thanks

  10. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #10
    Regulators can fail in several ways- in some cases, they can result in transient voltage or current passing to the ignition side of the system.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 46 years (learn something new every day).
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  11. Member
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    #11
    OK, since the regulator is new, should I isolate the tach? Is the tach the gray wire?

  12. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #12
    Tach is the gray wire. NEW does not necessarily mean "GOOD"... so I would DEFINITELY isolate the regulator to be certain.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 46 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor