1977 Johnson 140hp

Discussion in 'Bubba's Outboards' started by barney leonard, May 18, 2008.

  1. barney leonard

    barney leonard New Member

    Messages:
    109
    State:
    Mannford,OK
    I have a 1977 johnson 140hp that starts fine and idles around fine.My problem is when I give it more throttle it won't go up on plane.I do have a manuel and have looked all through it and can't figure anything out.Any help would be appreciated.
     
  2. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Do a compression check, and spark check, and let us know what you find.
     

  3. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    I would definitely suggest you follow BobPaul's suggestion. About 60% of a motor's problems can be determined by these two checks. You may also look for a spun prop. Saw an article on the board today by Bubbakat telling how you can check for a spun prop.
     
  4. barney leonard

    barney leonard New Member

    Messages:
    109
    State:
    Mannford,OK
    Thanks for the suggestions guys.I'm getting good spark and will check the compression later on in the week.When I've done that I'll let you know what I find out.Thanks again.
     
  5. barney leonard

    barney leonard New Member

    Messages:
    109
    State:
    Mannford,OK
    I did the compression check and have 105 on three and 100 on the other.I know this is getting close to the lowest point but what do you guys think should be the next plan of attack.
     
  6. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    If you have good spark on all cylinders then put it in the water and take the air silencer box cover off and while some one is running the boat lay two fingers up into the mouth of the carb and see if it picks up speed. If it does the the carb that picks up when you do this is dirty but rebuild both and not just one. Try flipping the choke on and off to see if this helps before trying the fingers and also you can try squeezing the primmer bulb to see if that helps and I have taken a squirt bottle and squirt premix into the carb throat while it is engaged and this will let you know if it starving for fuel.
     
  7. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Hang on tight when you do that. Just in case:smile2:
     
  8. Tight Line

    Tight Line New Member

    Messages:
    13
    State:
    IL
    Hey Barney,

    I had the same problem with my 83 johnson 140. Here are some things to check.

    1.) The compression, and spark.

    2.) Make sure your linkage adjustment is correct, my adlustment was off just enough and would not let the butterfly valves open up all the way.

    3.) Make sure that the carbs are clean ( rebuild carbs and remove air jets and idle jets ) use new carb kit gaskets and adjust the float correctly.

    4.) Make sure your prop shaft is not bent

    5.) Last thing i checked was the killer. I run a 131/2 x 20 stainless raker blade, and had dinged it a few weeks before i had the problem. Engine would idle well, but slam it down and it would not get on plane. Took the prop to a well known shop here in chicago and was told that if a raker prop is bent just a hair it will act that way ( not plane out ). Once fixed had no more problems. Plus went from 48 mph to 52 mph:big_smile:
    Just a few more thing to try and hopefully solve your problem.

    Tight Line