15 hp johnson fuel problem

[robertross]

have a 1981 vintage 15 hp johnson that will stumble and die when running at slow speed. does not happen at high speed. very infrequent but happens maybe once very 2 or 3 hours of run time. carb was rebuilt last year. i suspect the primer bulb or an air leak in the fuel hose. can anyone point me in the right direction. thanks.

 

[OBJ]

Re: 15 hp johnson fuel problem

Low speed needle could be adjusted a little to far out Robert causing it to run just a little rich. If you want to try and reset it, turn it in till it's gently seated and then back out 1 1/2 turns. Warm the engine up and run at WOT for a few minutes. Come back to idle and make your adjustments for best low end idle.

 

[Kev]

Re: 15 hp johnson fuel problem

Also could be fouling the plugs slightly after several continuous hours of slow speed running. Are you using the motor for trolling?<br /><br />You could try running the motor for a few minutes at high speed every 2 hours or so, and if you have no more problems with stumbling or dying at slow speed I'd say your problem was slight fouling of the plugs due to extended low temperature use.<br /><br />In any case, blowing the motor out every few hours is free and can't hurt.<br /><br />Also, go here for some awesome information on your motor:<br /><br /> http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000034 <br /><br />Good Fishin',<br />Kev