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Results 1 to 9 of 9
  1. #1
    Join Date
    Oct 2009
    Location
    Romney, WV, US
    Posts
    2

    Default "My 1988 Mariner 115 6 cylinde

    "My 1988 Mariner 115 6 cylinder will start and idle all day. It will run up to 1500 rpm no problem, but as soon as you try to throttle up above 1500 it will die. Occasionally you can sneak it past that point and it then runs great up to 5400 rpm. If you throttle back but stay above 1500 you can drop the throttle and it responds every time. It has acted this way since I bought the boat/motor. I've only had it out a few times, last time after rebuilding the carbs (which were perfectly clean and measured good for float height and needle drop, but I put all new in). Any ideas?"

  2. #2
    Join Date
    Jun 2009
    Location
    New Plymouth,Taranaki,New Zealand
    Posts
    287

    Default "Hi Michael,does it make any d

    "Hi Michael,does it make any difference if you squeeze the fuel bulb?idle mixtures lean? compressions ok? ."

  3. #3
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,200

    Default Your carbs' idle mixture m

    Your carbs' idle mixture might be set a bit too lean. Try opening each idle adjustment screw 1/4 of a turn and see if that helps.

    Jeff

  4. #4
    Join Date
    Oct 2009
    Location
    Romney, WV, US
    Posts
    2

    Default "I'll try making it rich b

    "I'll try making it rich by a 1/4 turn and hope I can get back to the lake soon. I take it from your suggestions that it is still running off the idle jets until about 1500. I haven't done comp checks yet but hope to this weekend. I initially assumed crud in the carbs, then the spark advance control box (which I read some folks think should be discarded... Do you agree?). Thanks for your help."

  5. #5
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    15,200

    Default "Try the carbs first. The tra

    "Try the carbs first. The transition from idle speed to 1,500 is about the time they start to open.

    Be sure to let me know how you make out!

    Jeff"

  6. #6
    Join Date
    Sep 2007
    Location
    Posts
    1,068

    Default The primary pickup timing is M

    The primary pickup timing is MUCHO important-O.
    Get the manual and do the link and sync.

    The box you refer to is the idle stablizer. That can be safely removed. You only need it when you have a big wheel prop. (20+")

  7. #7
    Join Date
    May 2001
    Posts
    1,678

    Default Another possibility is that th

    Another possibility is that the high speed winding on the stator has gone bad. You can check the voltage at the switchboxes. The red or red/white stripe is the high speed winding. The blue or blue/white stripe is the low speed.

  8. #8
    Join Date
    Jul 2008
    Location
    wareham, ma, plymouth
    Posts
    78

    Default I have an 86 Merc 115 that was

    I have an 86 Merc 115 that was having close to the same problem. I found the new gas we have was eating the seal in the two piece carb floats and it was filling the floats with gas. Easy fix get solid floats.

  9. #9
    Join Date
    Feb 2009
    Location
    perth, wa, Australia
    Posts
    956

    Default Go with Jeffs suggestion as i

    Go with Jeffs suggestion as i would suspect the carbies are set a little lean

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