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  1. #1
    Cadet
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    Default 1988 Mercury flooding itself on start

    I have a 1988 115 hp Mercury outboard that is hard to start hot or cold.. Its flooding itself on startup,.. then is loaded up and has to be cleaned out and then idles and runs perfectly thereafter. What it does is.. It fires right up, dies and will contine to crank unless you hold it about 1/4 - 1/2 throttle for about 4 or 5 seconds while cranking and it starts then dies and then after about two or three times of doing that it will stay running, its all loaded up, once it clears up after a few seconds, it runs great.. No problem loading up on idle, no hesitation. I have installed 6 new spark plugs and gone through all 3 carbs and made sure everything was adjusted to factory specs. Does anyone have any ideas on what I may do to correct this problem? Thank you

  2. #2
    Lieutenant Junior Grade hkeiner's Avatar
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    Default Re: 1988 Mercury flooding itself on start

    Since you are sure you have the carb jets and floats adjusted properly, you might consider checking for a weak spark when the motor is cranking but not starting. A weak spark can cause the flooding you describe.

    Is it possible that the motor is not actually flooding but is overloading on oil? If the oil injection system has a faulty check valve, the motor will be hard to start and smoke a lot at startup until the excess oil is burned off. Just a thought as this was a problem that I had on my motor previously. Here is a thread discussing that.

    1996 Mercury 150HP V6 carbed outboard motor and Maxum 1900XR bowrider boat

  3. #3
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    Default Re: 1988 Mercury flooding itself on start

    Have similar problem with 88 merc 90 horse 3 cyl.
    Mechanic replaced switch box (power pack?) ...better...will fire...but then stalls and seems to be flooded. Return in 15 minutes...fires,stalls. Sometimes with full throttle idle it will start in a cloud of smoke and keep running. Once it's started and warmed up it will restart in a heartbeat. These mercs are awful on cold start. Too much choke...floods...not enough choke or throttle...fires once, stalls,floods. Anybody got the knack for starting these?

  4. #4
    Supreme Mariner Silvertip's Avatar
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    Default Re: 1988 Mercury flooding itself on start

    Yes -- Cold Start Procedure:

    1) Squeeze primer bulb until firm.
    2) Raise fast idle lever about 1/3 up.
    3) Turn key to RUN (not start)
    4) Push key in for a count of eight (this primes the engine).
    5) Now turn key to START.
    6) When engine starts lower the fast idle lever to a slightly faster than normal idle.
    7) If the engine tends to die off in a few seconds, give the key a quick push to give an extra shot of fuel.

    If the engine does not immediately start at step 5, push in on the key while cranking for just a second or two.

    There is no automatic fast idle on a carbed two stroke so the mistake people make is not using the fast idle lever. Cold starts and flooded engines is what the lever is there for. If you do flood the engine, raise the fast idle lever full up. Flooded engines need air -- this action provides it.

  5. #5
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    Talking Re: 1988 Mercury flooding itself on start

    Thanks Silvertip...started up right away and continued to run using your 7 steps...great advice from the Fleet Admiral!
    I think I wasn't giving it enough choke...afraid it would flood...but the more i read on this forum....seems like they don't flood that easily...but won't start if not enough choke.....much obliged!

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