Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 7 of 7
  1. #1

    Default 50 hp Johnson Outboard - Engine cuts off after running wide open

    50 hp Johnson Outboard - Engine cuts off after running wide open for about 20 seconds. Both carbs have been taken apart and cleaned thoroughly. Idles well and runs good at lower rms. Tried adjusti.ng while on water and it does not seem to make a difference.

    Background: Motor was taken froma non running state(sat for a year or two). Now it starts up and sounds like it is running solid... But when you accelerate it eventually just cuts off. It will start again aftr about 5 minutes or so, but then does the same thing over again.

    Any ideas??

  2. #2
    Petty Officer 2nd Class
    Join Date
    Jun 2010
    Posts
    185

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    Sounds about like my boat.Check to see if the plugs are fouled.

  3. #3

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    Just to add more notes... I have cleaned carbs(even high speed jet in bottom of bowl as other posts have suggested) and replaced plugs.

  4. #4
    Petty Officer 1st Class pn's Avatar
    Join Date
    Apr 2013
    Location
    so. cal
    Posts
    300

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    others have noted that coils tend to loose spark after warming up. i really hope your not running lean you'll kill your motor in 6 secs

  5. #5
    Admiral
    Join Date
    Apr 2002
    Location
    Miami Fl
    Posts
    7,499

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    Could be several things - Start by squeezing the primer bulb as it starts to stumble. If it picks up you have a fuel problem - might be air leak in the fuel line, clogged vent at the tank etc.

  6. #6

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    Thanks for your responses. I plan to spend some time working on it tomorrow and troubleshooting.

    PN: What is the easiest way to check the coils to see if they lose spark? I have a basic inline spark tester, but not sure it will work for that.

    Solittle: Ill keep the primer bulb in mind next time in on the water. There is what appears to be a separate line coming off the tank that comes up and out by the transom.... It has a cap on it and it appears to have a screen/filter. Would that be vent and should cap be off of it? I have tried with and without the cap on.

    For some reason I want to say its getting flooded bc motor wont start again for about 5 minutes... But not sure... Just seems weird to work so well at lower rpms... But once i run hard for awhile it just dies.

    I plan to check and blow out fuel lines tomorrow and check some other basic stuff.

    Just curios... If the fuel pump was bad... Would it do something like this?

    Thanks again for your thoughts. Im stumped at the moment on this one.

  7. #7

    Default Re: 50 hp Johnson Outboard - Engine cuts off after running wide open

    Just did a compreson test. Top cylinder is 100 psi... And the bottom cylinder is at 150 psi. It is a Johnsonn 50 hp two stroke. Would this relate to issue?

Similar Threads

  1. 1993 25 hp Evinrude cuts out at wide open throttle
    By CrawPappy in forum Johnson & Evinrude Outboards
    Replies: 7
    Last Post: June 1st, 2012, 09:15 AM
  2. 1973 85hp Chrysler Engine surges after 5-10 minutes running wide open
    By trulyh8ful01 in forum Force & Chrysler Outboards
    Replies: 1
    Last Post: May 7th, 2012, 07:05 AM
  3. 1989 70hp engine not running wide open
    By wilson973 in forum Johnson & Evinrude Outboards
    Replies: 0
    Last Post: July 23rd, 2011, 09:11 AM
  4. '71 Johnson 50hp running wide open
    By LSUfan71 in forum Johnson & Evinrude Outboards
    Replies: 4
    Last Post: May 31st, 2005, 05:21 AM
  5. 9.9 cuts out at wide open throttle
    By pontoon chief in forum Johnson & Evinrude Outboards
    Replies: 5
    Last Post: August 15th, 2004, 06:20 PM

Tags for this Thread

  1. iboats Forum Directory - Over 100,000 forum posts organized by topic