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  1. #1

    Unhappy Help Please! 1999 Mercury 175 EFI Bogging on take off.

    i know this has been discussed a million times, but so far I can't find the exact symptoms or solutions. I don't even know where to start to troubleshoot the problem. Launched today and everything was fine at first. The hole shot was strong and got up on plane and was traveling at about 60MPH. Went for several miles and then had a couple of misses like I was letting off the throttle. Didn't think much of it because it happens sometimes. Did the same thing for 3 or 4 times during the afternoon only slight sputters at WOT. Then later on when it was time to leave, I idled out of a cove and hit the hot foot, Bog City! Tried starting and stopping a couple of times, but it kept bogging down. I did manage to get up on plane and ran it about 50MPH but the hole shot was Gone! New Filter/Separator, run Quikleen & Quikcare on every fill up. I have Not changed the Plugs in about 4 years. Should I start there or should I have someone look at the ECU? I will say, this has done this in the past but not every time. Sometimes it will bog on take off then suddenly spring into action at Full Blast!

    I'm including a photo of the serial number. I can't tell if they are Bs or 8s, maybe someone can.

    Any Help is Much Appreciated.


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  2. Member
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    #2
    Perform All of the required maintenance items, then report your results here.



  3. #3
    I've done everything except change the spark plugs. I assume that's what you're suggesting I do next...

  4. #4
    Well that didn't start off well. & before you say it, Yes I do have a Service Manual. I've never seen spark plug wires like this before. They seem to be integrated into the coils...

  5. Member
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    #5
    Start by replacing the spark plug then.



  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Plug wires are replaceable. Moving this thread over to the 2.5L Forum (correct forum for this engine).


    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
    might want to spark when problem is occurring , likely not gonna be a plug wire
    .................................................. ...the scariest thing in life is the unknown ...................................

  8. #8
    Changed the plugs. Ran Strong yesterday. No bogging or missing. Fluke? Who Knows? Hope Not!

  9. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #9
    Probably just what it needed- some of that "Annual Maintenance".


    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

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