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  1. #1
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    Mariner MagnumII 150 / Mercury XR4 2.4L carb/throttle linkage sync/adjustment

    I took the plastic throttle linkage off the 3 carbs to remove and clean each carb - engine now runs but idles way high. I know I didn't get this plastic throttle linkage on correctly - probably have the throttles cracked open.

    I notice it's slotted where the bolt to connects it to the throttle blades. Do I just install it so that the throttle blades are completely closed at closed throttle? It's not like a car where you need a minimum throttle setting to keep the throttle cracked open just a hair? I did notice that the throttle blades all have about a 1/4" hole in them (from the factory) so I'm guessing the blades should just be closed completely?

    Just wondering how I should set this up in that slot. Pics are of the plastic throttle linkage connecting the 3 carbs and a closeup of the slot without the bolt installed. I've searched the forum archives and don't find this info anywhere. Thanks for any help! (also posted on marineengines.com)
    closeup.jpg20200629_120356 small.jpg

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #2
    If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the REQUIRED Info (serial number) when posting. Thanks!

    If the carbs are loosened or removed, a COMPLETE Sync-n-Link (all steps shown in the "Engine Synchronization and Linkage Adjustment" section of the Mercury Service Manual) must be performed.

    The carb linkages and roller are synchronized by utilizing the phillips head screws (be VERY careful- if over-tightened they will crack or break linkages- appears one is already cracked, and the top carb may actually be missing the screw/washer).


    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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  3. Member
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    #3
    Thanks for the reply. Could someone please put a sticky at the top of this forum showing where to find the serial number on these engines? I've looked and cannot find it.

    Yep - the plastic is cracked so they must have been overtightened before. The top carb is missing the screw because I took it out (first step in removing the carbs to clean them) and realized I'd better take a picture.

    I've seen references to Sync-n-link elsewhere but haven't found a link on how to perform the procedure. I don't have the service manual. Could someone post the procedure? Thanks.

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Since the specifications and linkage layouts vary from one engine to another, you NEED to obtain the correct OEM Mercury Service Manual based on your engine's serial number.

    Serial number is affixed to a light gray tag on the Swivel Bracket (usually STB or right side). May also be stamped into an approximately 1" welch plug on the powerhead (top or Starboard side).


    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
    I think I found the serial number, is this it?
    serial number.jpg

    I think it says 088347? What does this indicate? Model year?

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Serial Numbers are normally formatted: Digit, Letter, Six Digits (Example: 0D123456, 0B123456). In some cases you may not have the "zero" for earlier engines (or it may be all numeric, but have at least 7 Characters).


    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 looked over the engine and am still unable to find the seriel number. From what I have read, it seems as if there should be a plate with the model and serial numbers on the transom side of the engine. I took some pictures of the engine where I think it should be located showing that there is nothing there. However, I did find a string of numbers on the transom side of the engine mount, but have a feeling those won't help much either. Any other hints to where I should look?

    potential serial number .jpgport side transom mount .jpgtransom mount.jpg
    Attached Images Attached Images
    Last edited by thrashercharged; 07-07-2020 at 02:02 PM.

  8. Member
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    #8
    The sticker/placard is usually on the transom side of the mount. Could have been lost/removed.

    On the third picture it would be below where you see the Boysen sticker, on the bracket that attaches to the transom. It’s usually not hard to see if it’s still present, unles painted over.
    Mercury 2002 200hp Carbed Saltwater
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  9. Member
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    #9
    While it may not help you, it might help others when asking same question, sticky topic in the Mercury forum just above this one - How to find your serial number on your Mercury outboard
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax