Rough Idle

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chaddeems

Seaman Apprentice
Joined
May 3, 2005
Messages
48
I have a 1989 Four Winns W/ 4.3 OMC Cobra. The engine is freshly rebuilt with the original carb that ran perfect last season. the engine is hard to start and idles rough. Also sometimes when i go from stop to full throttle is bogs out. I am going to test the ESA tonight but i have only a couple of hours today before my brother in law take it for the week so i would like to fix/ adjust as mush as i can. obviously a carb rebuild is out for the question for right now but does anybody have any other suggestions that i can try tonight to get it to start easily and fix the idle?
 
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hoot

Chief Petty Officer
Joined
Sep 8, 2002
Messages
434
Re: Rough Idle

check the basics. replace fuel filter, check timing, carb settings, point gap, plug gap and condition? coil going bad? may need a carb rebuild later.
 
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Olds Eddie

Petty Officer 2nd Class
Joined
Jan 30, 2005
Messages
194
Re: Rough Idle

Could be an intake gasket leak. You mentioned that it was recently rebuilt and if the intake is loose or the gaskets arn't quite right it will cause these symptoms.
 
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chaddeems

Seaman Apprentice
Joined
May 3, 2005
Messages
48
Re: Rough Idle

new fuel filter, new plugs - gapped, new points - gapped, timing dead on, the card setting are untouched<br /><br />How can i check the coil going bad? I am planning on rebuilding the card after i get the boat back from my brother in law
 
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SeaSkwurrel

Petty Officer 3rd Class
Joined
Sep 20, 2003
Messages
75
Re: Rough Idle

The hard starting and bogging out could be an accelerator pump failure.
 
Ron Everson

Ron Everson

Petty Officer 2nd Class
Joined
Apr 18, 2003
Messages
114
Re: Rough Idle

My 1975 225 OMC (305 Chevy) started hard when cold for years. Finally took it into the shop a few weeks ago and they discovered a split in the fuel line where it connects to the fuel pump intake. Fuel pump wasn't able to suck enough fuel from the line because of air leak. They cut off a short section and reattached it and voila! it now fires right off when cold just like when it's warm. Funny I never smelled or noticed a gas leak, so it must have just allowed air into the system.
 
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Richard Petersen

Senior Chief Petty Officer
Joined
Dec 17, 2004
Messages
778
Re: Rough Idle

Flat spot on a quick shove to full throttle is usually a worn out accelerator pump diaphram.
 
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