2001 90 hp Johnson rough at 3000rpm

[ermess]

90 hp idles fine, put it in gear and bring to 3000rpm engine sounds really rough, bring it to WOT she smooths out and runs fine. Take her out of gear and bring rpms up to 3000 she sounds smooth.
When running in gear at 3000 rpm sound seems to get worse when steering back and forth. Plugs look fine compression 120 on all cylinders. Prop, carbs, powerpack?
Thanks ED

 

[91cajun]

Re: 2001 90 hp Johnson rough at 3000rpm

Sounds like crud in your carbs. I have had some success running Marvel Mystery oil mixed in a separate gas tank to clean out some of the crud. If that doesn't work probably need to get the carb kits and clean, rebuild the carbs.

 

[91cajun]

Re: 2001 90 hp Johnson rough at 3000rpm

One thing I forogot was checking the fuel lines for loose or cracked clamps. If it's sucking air that may be part of the problem.