Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 4 of 4
  1. #1
    Cadet Registered
    Join Date
    Jul 2011
    Posts
    2

    Default 1967 johnson seahorse 20hp power problem

    model fd-21r, runs great a low speed and when turn to wot will start to power up then acts like its bogging down and wont plane out. have changed points, plugs and wires, coil, and put in carb kit. still acts the same, help! btw pumping fuel bulb makes no change except it starts to act like its flooded then.

  2. #2
    Captain jbjennings's Avatar
    Join Date
    Jul 2007
    Location
    northwest Louisiana
    Posts
    3,601

    Default Re: 1967 johnson seahorse 20hp power problem

    How did you check spark? Did spark jump a 1/4" air gap with a hot blue spark on both cylinders?
    If spark is good, then you might check to see that your float needle is closing off when the bowl is full, or that your float is adjusted so that the bowl is filling up. Did you replace the donut gasket on the post in the center of the float bowl?
    Just some things to check,
    jBJ
    Not a certified mechanic but I have at least 2 shade trees in my yard and my wife always says I'm certifiable. So remember that when you follow my advice

  3. #3
    Cadet Registered
    Join Date
    Jul 2011
    Posts
    2

    Default Re: 1967 johnson seahorse 20hp power problem

    spark tested with spark tester, good jump and hot blue, havent checked to see if float needle is closing off when bowl is full, did make sure that float was level when upside down when torn apart, and it was missing the donut gasket when i pulled it apart and i replaced it. just wondering if i missed some debris when cleaning carb in the small holes, only had carb cleaner and no air, which i knew was a mistake at the time. thanks for your help

  4. #4
    Petty Officer 1st Class
    Join Date
    Aug 2009
    Posts
    318

    Default Re: 1967 johnson seahorse 20hp power problem

    i think there is a problem with the cam follower on these motors. It gets worn and the carb doesn't open open up completely. i had to make a new wire that connects the cam follower to the throttle valve, 1 mm longer made a huge difference in performance. also, it could be poor air circulation, the motor is breathing its own exhaust, like when running in a barrel.

Similar Threads

  1. Need advice on 1967 Glasspar w/ 1967 Johnson Super Seahorse 80
    By BonairII in forum Johnson & Evinrude Outboards
    Replies: 3
    Last Post: July 26th, 2011, 05:07 AM
  2. 1967 Johnson 20HP Outboard Shifting Problem
    By klynn55 in forum Johnson & Evinrude Outboards
    Replies: 3
    Last Post: May 25th, 2011, 06:56 PM
  3. Johnson Seahorse 20hp (1971) losing revs/power at WOT.
    By maurizio in forum Johnson & Evinrude Outboards
    Replies: 0
    Last Post: August 5th, 2009, 04:20 PM
  4. 1967 Johnson Seahorse- No Power at WOT
    By miklor73 in forum Johnson & Evinrude Outboards
    Replies: 1
    Last Post: June 16th, 2009, 07:15 PM
  5. hello!newbie!1967 johnson seahorse 20hp starting question
    By jay42782 in forum Johnson & Evinrude Outboards
    Replies: 17
    Last Post: September 23rd, 2008, 10:55 PM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic