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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 25638
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a John Deere L130 with a 23 HP Kohler Command engine.

Resolved Question:

I have a John Deere L130 with a 23 HP Kohler Command engine. The mower is sputtering and blowing black smoke. It idles fine and if a throttle up slowly it does not sputter but as soon as I press the accelerator it sputters and blows black smoke. The spark plugs are black and wet on both cylinders. How can I fix this?
Submitted: 6 years ago.
Category: Small Engine
Expert:  Curtis B. replied 6 years ago.
All indicators are the engine is flooding, but with the carburetor already cleaned. Maybe something else is going on. How did the problem develope? Gradually, or did it come on all at once? Did it start acting up after some kind of incident, ran over root, killed engine, etc.. How old is unit? Hours? Unit should have hydraulic lifters, so valves don't need adjustment. What is the rest of the story? Let me know. Thanks.

Edited by curtis beason on 7/6/2010 at 4:08 AM EST
Customer: replied 6 years ago.
Thanks. The machine has 160hrs. The unit is a 1994 model. I bought it used after having sat for over a year--at this point the engine cranked but did not start. After I cleaned the carburetor it started but ran with sputtering and black smoke. The gentleman that sold it to me indicated that it was working fine when he stopped using it.
Another observation is that the carburetor is spitting gas when the engine begins to sputter--I tried to adjust the air/gas mixture screw but had no effect on the carb nor engine. If the engine is running at idle the air/gas mixture screw will kill the engine if I turn the screw all the way in. If the engine is running at full throttle the air/gas mixture screw has no effect on anything.
I had read on a blog that to get rid of the sputtering the air/gas mixture had to be balanced with the adjustment screw but in this case this screw does not work. Would a new carb work better? They are kind of expensive and would like to ensure that's what I need before I buy one.
Expert:  Curtis B. replied 6 years ago.
Check the exhaust for restriction, here in Texas, if you let anything sit for a year, it will have mud dauber nests in anything that has a hole. If the exhaust is open, I would pull the plugs and run a compression test, it won't be a big help, but it will tell you if the cylinders are equal. With built in compression release, you won't get a high reading. When I see an engine not taking gas, and spitting back through the carb. , I think it is not pulling a good enough vacuum to pull the fuel into the cylinder. Also, does it still have the electric fuel shutoff solenoid in the carb. base? These things can cause erratic fuel supply. If it still has it, pull it out and check its operation to determine if it is retracting each time the key is turned on. Let me know. Thanks.
Customer: replied 6 years ago.
Thanks Curtis, I'll do what have suggested. You mentioned "not pulling a good enough vacuum..." are there vacuum hoses I need to check?
Again, Thanks.
Expert:  Curtis B. replied 6 years ago.
No, there are no vacuum lines, I was just talking about the cylinder, that is how the cylinder gets the fuel, it sucks it in, if the valve is open, no suck.
Customer: replied 6 years ago.
My apologies for being so late in responding. The compression in both cylinders is low but about the same.
The exhaust is open. The solenoid at the base of the carb is free and operating--initially it was stuck in place due to a very sticky (brown) substance. I went through the carb again letting soak almost two days in (Gunk) cleaner and used air pressure to dry it. Now I can adjust the idle speed but not the air/fuel mix screw. Having tried just about what I know and your suggestions and still have sputtering gas out of the carb (these will be my last questions on this issue) could I have a bad carb or a leaking head gasket?
Curtis I appreciate your help on this and know that I will accept your next answer so you get paid for your efforts.
I may just have to take it to a service center. Ouch.
Expert:  Curtis B. replied 6 years ago.
Did you run a wire through all the ports in the carburetor when you were cleaning it? With the gas still coming out the carburetor, and knowing the unit was not used for awhile, I am thinking the valves are leaking from buildup of rust or gunk over the storage period. It is probably going to take removing the heads and reseating the valves to get unit to run correctly.
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