115 johnson sputtering at idle speed any ideas?

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atlapp

Seaman
Joined
Sep 25, 2010
Messages
51
i have a 1991 tracker with a 1992 115 johnson pro series that runs great while at full or partial speed, however after a long run down lake i slow down to idle speed to look for structure on sonar and motors makes a spitting sound and will sometimes die then it seem difficult to get restarted. carbs were just cleaned with new seats and valves, new fuel filter and lines. any ideas what may be the problem? thanks in advance!!!!!!!!!
 
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emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 115 johnson sputtering at idle speed any ideas?

A sputtering at idle could be a "lean sneeze." This is a carb issue. At idle the carb butterflys are completely close and the carbs draw fuel from special idle circuits (passageways in the upper carb body.) If these get plugged with debris (dried fuel) it will sneeze occasionally at idle and may idle poorly. The only way to rectify this problem is to overhaul the carbs-making sure the idle circuits are opened up. An aerosol carb cleaner does the trick, cleaning out any dried fuel. Once the throttle plates open slightly, the carbs draw fuel from the other jets and it may run just fine at higher rpm's.
 
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Haffiman

Commander
Joined
Dec 17, 2009
Messages
2,454
Re: 115 johnson sputtering at idle speed any ideas?

When did you last check/change water pump and thermostats?
If the bypass-valves hangs or thermostats do not close fast enough, engine temp drops and symptoms like you describe may occur.
 
A

atlapp

Seaman
Joined
Sep 25, 2010
Messages
51
Re: 115 johnson sputtering at idle speed any ideas?

i just got this boat about 4 weeks ago, seems to have a nice flow of water, also has a psi gauge 10 at idle up to 25 at wide open, so i think water pump is ok, i also know carbs were cleaned right before i purchased, i'll try the carb cleaner and see if that helps
 
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