Carb clean/rebuild???

Discussion in 'Outboard Maintenance' started by richwalker71, Sep 14, 2011.

  1. richwalker71

    richwalker71 Well-Known Member

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    My 99 25hp Merc is having a couple issues:
    First, intermittently after running at speed, when I come back to neutral it will idle way above normal RPM.  This started several weeks ago.
    Now as of yesterday it will not hold at anything close to WOT. Idles good (with the above exception), comes out of the hole fine, then as I start to  trim her out she will slowly lose RPM.

    Is a little carb work in order?
     
  2. noeettica

    noeettica Well-Known Member

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    Run it wide open while running on the water ... pull kill lanyard drop anchor and read plugs ...you may have an air leak ...just my opinion ...

    Never hurts to go through carb ... watch out for tiny balls ... easy to loose :-(
     

  3. richwalker71

    richwalker71 Well-Known Member

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    Watch out for tiny balls! Always good advice. :D

    Thought about the possible air leak. Gonna run a test tank/hose tomorrow.
     
  4. DuckNut

    DuckNut Brandon, FL

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    I get issues similar to this once in a while and I have had extremely good luck by running a can of premix gas by Stihl through it. About $10 a gallon but has prevented me from a rebuild.
     
  5. richwalker71

    richwalker71 Well-Known Member

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    Ok. Pulled the plugs for a look see. Top looked fine, bottom has deposits from running too lean. Is it normal for them to be different?
     
  6. richwalker71

    richwalker71 Well-Known Member

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    Didn't think so. So what are the possible problems causing this?
     
  7. noeettica

    noeettica Well-Known Member

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    check compression .... if equal then look for an air leak
     
  8. richwalker71

    richwalker71 Well-Known Member

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    I'm certain its an air leak. Now I gotta find it!