1967 johnson seahorse 20hp power problem

P

ptown

Recruit
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Jul 18, 2011
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2
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.
 
jbjennings

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
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
 
P

ptown

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Jul 18, 2011
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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
 
R

restornator

Petty Officer 1st Class
Joined
Aug 15, 2009
Messages
361
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.
 
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