Rough & irregular idle

[Plank]

I own a 2001 90 hp Johnson. Always ran right from new. Yesterday started it on muffs before going to water and it started fine, ran fine until it warmed up to the point where it usually idles down to 700 or 800 rpm. At this point it started running between 1000 & 2000 rpm, coughing and spitting until i shut it off. If i shut it off and let it cool and start it again it does it all over again.

 

[Joe Reeves]

Re: Rough & irregular idle

The usual cause of that problem is that when the Fast Start mode drops out as the engine reaches operating temperature, the rpms naturally drop down as you state..... but the carburetors are somewhat fouled which results in a lean mixture setting, especially in the slow speed passageways.<br /><br />That condition results in having the engine respond exactly as you describe.

 

[Plank]

Re: Rough & irregular idle

Thanks Joe Reeves. Do you think a complete rebuild is in order, or is there some other way to cure problem. Thanks

 

[Cricket Too]

Re: Rough & irregular idle

Your best bet is to do a complete rebuild, that way you know they are clean and running properly, a lean running carb can destroy your motor before you know it. Good luck