3hp OMC crankcase question

[stanley]

If every thing else is good(compression,spark,rebuilt carb),can a leaky crankcase cause an extremely rich running condition?My assumption was it would only cause a lean condition.

[fleetwin]

Yeah, a leaky crankcase will most likely create a lean condition…Tell us more about the rich running condition…

[stanley]

Won’t start without shot of fuel into intake,but won’t run without low speed needle closed and high speed out 1/8 turn.Runs well throttled up but not below start position.Obviously flooding out with wet plugs and lots of smoke.The reason I asked is It did the same with carb from another motor.Spark jumps 1/2 inch gap.

[billw]

Are you testing using the sound attenuator, and on both carbs? If so, maybe the attenuator is plugged up with an insect nest? Sorry if that is too obvious but it’s all I can think of, other than two bad carbs.

Long live American manufacturing!

[stanley]

Used attenuator both times and made sure it was clear.It’s such a simple motor but I’m stumped.Next step is putting carb and mag plate on known runner power head

[mercuryman]

There is a gasket between main jet and float bowl it can leak and cause rich. It needs to compress when you tighten float bowl.

[outbdnut2]

Yup – that gasket Mercuryman mentioned looks like a small, thick, compressed fiber washer, and it can fall on the floor when the carb gets disassembled or re-assembled, but my experience with missing "donut" carb gasket is OK at idle, floods and quits when throttle is advanced. With your symptoms, I’d say the gasket is there but not sealing completely. It sits at the bottom of the casting that extends down through the hole in the float. When you screw the float bowl to the carb, if you carefully squeeze the bowl to the carb first, you can feel this washer compress. It prevents gas from bypassing the high speed jet.
Dave

[stanley]

Yes I made sure to put a new nozzle washer in,but had the same thought as far as not sealing properly.The fact that the symptoms didn’t improve with another carb,however makes me think that in spite of good spark it might be some electrical issue.The puzzler is it needs fuel to start,but is flooding at lower speeds.Oh well,that’s why this hobby is more fun than cross word puzzles or soduku.

[Mumbles]

Has the carb been synchronised to the magneto correctly? Johnsons have two little dots on the gas tank ring and the speed control lever must be in between them just as the carb butterfly is starting to open. Evinrudes are done slightly different.

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[stanley]

Yes, it’s been synchronized.

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