15 hp Johnson - High Speed

[101 waterway]

Have a 1994 Johnson 15 HP outboard, that labors from 3/4 to full throttle. Starts on one pull and runs great unitl 1/2 speed. History. About 4 years ago, gas was left in over winter. Took into dealer and carberator etc was cleaned. From that time on the problem started. Some folks have said rebuild carb. others coil cracked. Have never left gas in the engine since the first time, when winter came on fast. Any thoughts?

 

[janichol]

Re: 15 hp Johnson - High Speed

I've got a 99 Johnson 30hp that does about the same thing. Starts like a champ, get's my 15' Lowes up on plane quickly, but when I throttle back to cruise, it will run but drop rpm then go back up again. No sputtering, just a clean drop of about 500 rpm. I thought it was a heat problem, but replaced the impeller (which was shot after 3 years in salt water), but it is still running the same... just a little cooler.<br />(I just bought this motor, don't have any history other than to notice that none of the bolts have ever been broken on the case).<br />Does your motor run at full throttle? Your post indicates it runs good to 1/2-3/4 throttle, but not sure at full.

 

[alcan]

Re: 15 hp Johnson - High Speed

Hi101<br /> Did you notify your dealer of the problem? If not why?

 

[Solittle]

Re: 15 hp Johnson - High Speed

WATERWAY - I would do the carb and do it myself. Unfortunately many mechanics will clean it so it looks good on the outside but that ain't where the problems are. Buy the kit - they ususlly come with a parts diagram. When you disassemble it make sure that you remove every piece including the little plugs as in my limited experience the dirt that gets you is the dirt that you can't see. Soak all the parts in a parts cleaner solution that you can get from an auto parts store. When you think everything is sparkeling clean, find domeone who has a high pressure air compressor is you do not have one and thoroughly blow every crevice, hole and especially the little fuel passages.

 

[clanton]

Re: 15 hp Johnson - High Speed

Check the throttle cam on the timer, made from plastic, sometimes breaks will not open throttle completely. Check plastic link and roller on top of carb, these also break and will not throttle completely.