99 Johnson 90Hp Rough Idle, Stalling and Unusual Vibe at Mid Range RPM

ncskains

Recruit
Joined
May 15, 2010
Messages
2
Good day all,

I have a 90hp Johnson ive been trying to troubleshoot since last summer now. The engine was running great untill last summer i was running skirting around an island and found my self in a kelp bed, i was traveling about 1/4 throttle when i noticed the a rapid decrease in water depth, so i pulled the motor back quickly and threw it in reverse to prevent running aground. Anyways on the way back in i noticed an unsual vibe that last for a bout 1-2 seconds and then goes away then comes back again about 10 secs later. Also ever since then the boat doesnt want to idle worth a crap and also stalls frequently..

So what i have done, replaced water sep, checked all fuel connections, no leaks, cleaned carbs, replaced and re-gapped spark plugs.. Still no change in idle. Any ideas what could have caused this?? Thanks in advance.

-Nate
 

ncskains

Recruit
Joined
May 15, 2010
Messages
2
Re: 99 Johnson 90Hp Rough Idle, Stalling and Unusual Vibe at Mid Range RPM

Looking for any guidance, thank you!
 

catch&release

Recruit
Joined
Jun 11, 2010
Messages
1
Re: 99 Johnson 90Hp Rough Idle, Stalling and Unusual Vibe at Mid Range RPM

I've experienced the same rough idle for 2 years. I bought mine used and just thought I'd been screwed by the previous owner not properly maintaining the motor. Sounds like that may not be the case.
 

mamm7215

Petty Officer 2nd Class
Joined
Apr 28, 2010
Messages
184
Re: 99 Johnson 90Hp Rough Idle, Stalling and Unusual Vibe at Mid Range RPM

Well, before you go spending any more money, I would do a compression test.
 
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