Could this be causing my idle lean condition?

gwoloshyn

Petty Officer 2nd Class
Joined
Jul 27, 2010
Messages
184
1992 Johnson 150 hp
TJ15OGLENC

I'm working on this motor that is giving a slight lean sneeze at idle, and at trolling speeds in the water. It will slightly sneeze, but only when in gear and at trolling speed. In other RPM ranges, mid to WOT it will run great.

I've gone through and cleaned all 6 carburetors, paying close attention to the idle circuit and all the small passages. I'm sure the carbs are clean BUT what I found looks like worn rubber covers that go over what I believe to be the idle circuit. Could this seal be letting air in from somewhere whether from outside or within the channels causing the engine to run lean if it wasn't installed in the exact same spot it was before? Here is a pic of it:

sd (1632 x 1224).jpg
 
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boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
Re: Could this be causing my idle lean condition?

See that hole in the gasket on the lower right side. When you put the cover and a new gasket back on, get a thin wide body washer and put under the screw that holds it. This will help seal the cover. The later covers had 5 screw holes in them.
 

gwoloshyn

Petty Officer 2nd Class
Joined
Jul 27, 2010
Messages
184
Re: Could this be causing my idle lean condition?

Thanks for the tip. I'll order new gaskets but would you say this could likely be my issue since it's only leaning out at low speeds? Im fixing this for a friend and dont want to throw parts at it unless its really the problem.

The plate is actually aluminum not plastic. But I'll try the washers anyway.
 
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boobie

Supreme Mariner
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Nov 5, 2009
Messages
20,826
Re: Could this be causing my idle lean condition?

Part of your idle circuit is under that gasket. I goofed up, The washer goes under the hole that is closest to the center at 11:00 position in your pic. The newer carbs had 5 screws for the cover
 
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gwoloshyn

Petty Officer 2nd Class
Joined
Jul 27, 2010
Messages
184
Re: Could this be causing my idle lean condition?

Ok thanks I will give it a shot once my new gaskets get here.
 
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