smoke from top carb on 70hp Johnson

[dfrants]

got a 1979 70hp Johnson that was running great this spring, now dies out at idle. went through the carbs, they look good, ran it today without the air box cover and noticed that after she dies out exhaust smoke exits out the top carb. is this normal? if not, what should I be looking at? she has great compression for her age.

 

[boobie]

How did you go through the carbs ??

 

[daselbee]

The reeds will be closed when the engine is stopped.
So if he is getting exhaust or even just fuel/air vapor out the top carb EVERY TIME, then I would suspect a reed problem on the top cyl.

Also would cause seriously bad running....stalling...no idle, etc.

When running, is gas spitting out the top carb? Raining out?

 

[fireman57]

pull the carb again and get a flashlight and shine it into the reeds. I bet you will find a small bolt from the carb cover back there.

 

[dfrants]

puzzling...I pulled the top carb and the reeds look good. poked my finger in there and flexed each reed...seems good. could a something pass through? going to reattach everything back together and see how she goes.

 

[interalian]

Shouldn't poke the reeds - easy to damage if you push too far.

 

[emdsapmgr]

Probably normal. You did not say that you noticed a slight spray of fuel/oil burping from the top carb venturi every so many rpm's. This is a characteristic of the OMC 3 cyls engines. The internal oiling galleys terminate inside the top of the intake manifold. Anyway, as the engine oils itself internally, some leftover fuel/oil spits out of the top carb. Drops to the bottom of the airbox, where it is recircualted into the bottom cyl. That's normal.