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  1. #1
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    2018 150 Four Stroke 2b544121

    Motor on rt 198p Ranger and currently idle speed is 4.5mph or higher and tach reads 900+ on boat console! The dealer says the tach is reading high, but changing tach will not slow boat down? I am trying to see if others with this combo are having this issue.....should I expect the tach to change this?

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #2
    Do you have any type of Smartcraft Instrument on board this boat? What is the tach reading on SMARTCRAFT?


    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).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  3. Member
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    #3
    No Smartcraft on boat that I know of unless it is hidden somewhere on Lowrance unit? Are you aware of that kind of idle speed on that boat combo....can't seem to get anyone to tell me if that is just where I am going to be?

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Engine idle speed is controlled by the PCM. 650 +/- 50 RPM's is what it is aiming for.

    Prop type and pitch (combined with hull type and weight) will affect how fast the boat is propelled at idle speed.

    Since prop pitch is selected based on WOT RPM's, this isn't really "adjustable", with the exception of utilizing "Troll Control" on a Vessel View, MercMonitor, or SC-1000 Series product.


    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).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  5. Member
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    #5
    Doesn't this engine also have idle charge management, so the engine may bump up the RPM's if the alternator load is high or battery voltage low, to try and recover some charge? So, if the battery were marginal, maybe that is contributing?
    2016 Ranger 1850 LS Reata / Merc 150 4s / SmartCraft / Lowrance HDS Carbon SS3D

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    That is a possibility, though it most commonly is over-ridden when you attempt to shift.


    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).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  7. Member
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    #7
    I have same motor........I looked at my idle rpm yesterday several times.....it was always 650 on the mercury smart craft.