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The engine starts easy and purrs like a kitten for about ten seconds. Then it runs rough and black smoke comes out of the exhaust as it is getting too much fuel.

Why does it run like a charm for the first ten seconds or so then acts like the choke is engaged?

Thanks in advance! :smile:

Is it "acting" like the choke is engaged or is the choke actually closed?

A lot of engines from a cold start with full choke will run smooth for a few seconds and then load up as then engine can't digest such a rich mixture.

I removed the air filter stuff and the choke is working fine. The manual choke knob opens and closes the choke on the carb with ease.
The rider starts up very quick. I drove it around the two lots a few times and it feels and smells like it is getting too much fuel. After the initial startup it takes around ten seconds or so for it to start running ruff with a dark smoke coming from the exhaust.

If I let it sit for fifteen minutes or so it is back to the same thing. The initial startup is smooth. Give it a short amount of time it runs noticeably rougher and the dark smoke is visible. It is not a heavy smoke. However, it is visible and smells like the choke is engaged and stuck, which it is not.

Another thing worth mentioning, last fall this mower quit running while cutting the grass. I tried several things to get it going again and eventually put it away for the season. When I got it out last week I charged up the battery, dumped fuel directly down the carb throat and, after doing this a few times it finally kept running. I verified fuel is easily passing thru the fuel line from the tank, the new fuel filter and to the carb, which it is. I also put new Champion spark plugs in it.

Remove the dipstick and see if the oil smells like gas. If there is gas in the oil, it will start pushing gas vapors through the breather into the intake making it act like it is running rich.

Thanks for the idea!

Not the oil. I changed it and the engine still doing the same thing.
Really thought this would be the cause!

Tossed the rider up on CraigsList today and it was sold in a few hours. Not my problem anymore.
Could have sold a half a dozen of them today if only I had 'em :smile:

Thanks to all who contributed with suggestions! :thumbsup: