Mercury outboard problems

Discussion in 'Bubba's Outboards' started by elalr, Jul 29, 2006.

  1. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    i was wondering if any one had any suggestions for a 1974 model 65 hp merc that wont stop fouling plugs. i mix fuel at 50:1 ive replaced plugs twice and i replaced the switch box when i bought the boat in the spring. i have also removed the carbs and had them cleaned any help would be appreciated. also on a side note sorry i dont have an avatar up yet. hope to have it up tomorrow. thanks again
     
  2. Mr.T

    Mr.T Active Member

    Messages:
    2,554
    State:
    MO
    Try a hotter spark plug. And verify that the mixture isn't too rich.
     

  3. Arkie55

    Arkie55 New Member

    Messages:
    669
    State:
    Mississippi
    Larry,
    Are you running fire ring plugs (without electrode) or regular electrode type marine plugs? Mercs were designed for the fire ring type plug.
     
  4. FishMan

    FishMan New Member

    Messages:
    2,293
    State:
    Tennessee
    sounds like your problem lies in the plugs. it need a certin type but a hoter plug will foul even quicker if I am thinking right
     
  5. tspergin

    tspergin New Member

    Messages:
    867
    State:
    newark ohio
    dont want to up heat range too much on a merc they will burn a hole thru no 1 piston pretty quick, try decarbing the engine and using the specified plugs,if that doesnt work sounds like rings are bad or stuck,hope this helps you out.Check at a dealership and ask for some carbon blast
     
  6. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    the first time I got the specified plugs which are electrodeless. the second time i got the next hotter plug which is the hottest in that range. the oil mixture is right for sure ( I double checked and I also had someone else figure it for me to be safe). the first tank of fuel was possibly wrong mix. it was in it when i bought it.(should have dumped it). I have now ran one tank through it of the right mix. it still smokes also thanks again for the info
     
  7. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    The plugs you people keep mentioning are termed "Surface Gap".

    Get your timing checked, insure that your getting the right voltage to your switch box and coils.

    Do as suggested and get the inside cleand out and the rings freed up. Do a compression check first then do one after the decarboning.

    Switch to a quality synthetic oil.
     
  8. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    You can decarbon that ole dog with seafoam and those older mercs like ngk plugs.
     
  9. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    what is sea foam, ive never heard of it, and thanks for all the advice
     
  10. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    I never even considered the timing thanks
     
  11. duxsrus

    duxsrus New Member

    Messages:
    1,014
    State:
    SW Ohio
    Yep, and you don't mention if this is a "new to you" boat or not. I would consult the NGK website and use the plugs they mention on there. My buddy bought a used boat once and it never ran real spectacular, come to find out , the previous owner had incorrect plugs in it.

    Try this link:

    http://www.ngksparkplugs.com/apps/watercraft/default.asp?nav=60000&country=


    Good luck.
     
  12. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    thanks for the link. I just checked it out and I do have the right plug. it is a new to me boat. 1974 model. i also have NGK plugs. it will idle fine not much smoke but when you take out it will almost get up on plane before it will start messing up. its like someone pulled it to half throttle. thanks again
     
  13. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Sounds like it's over fueling. If and when I get new to me engines, I'll always clean the carbs and set them up, along with timing advance, AKA sync and link. Very important to good running engines.

    This is not a definate fix, but worth checking into.
     
  14. elalr

    elalr New Member

    Messages:
    193
    State:
    warsaw missouri
    thanks alot for the advice. i will procede. maybe that will fix the problem