B&S 20 hp sputtering at high rpm

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  #1  
Old 05-16-08, 11:04 PM
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B&S 20 hp sputtering at high rpm

Hello:

My new 2007 Craftsman tractor with a B&S 20 hp started this season fine although I failed to perform the season ending maintainence aside from changing the oil. I got one good cut this year and then the trouble started. I had a large puff of white smoke once during the second cut. Afterwards it was fine. I then had problems starting the engine the next week. Today I changed the plug, fuel filter and the oil (to be sure I didnt overfill when I changed it last year. I used it already this year so I am not concerned about old gas. The problem that I have now is that while the motor starts and runs fine at a lower speed, it sputters in the highest setting, just before the choke setting. The sputter is more like a miss that occurs every five seconds or so and it only happens at very high rpms. My thought was that the throttle somehow became misaligned, however, when the choke is engaged, even minimally, it is obvious. Any thoughts are greatly appreciated.
 
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Old 05-17-08, 12:55 AM
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Is the air filter clogged or oily? Does the oil smell like gas?
 
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Old 05-17-08, 07:50 AM
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Sorry, I left out that I replaced the air filter although the old one looked and seemed to be perfectly fine. There was no odor of gas either.

Thanks Again.
 
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Old 05-17-08, 06:29 PM
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new update. The new oil does indeed smell like gasoline
 
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Old 05-18-08, 12:11 AM
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The carb is flooding, due to trash in the needle/seat area, or a bad needle/seat, or possibly a sticking float.
 
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Old 05-18-08, 11:52 AM
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Thanks so much. I sprayed some carb clean in there and around the outside. The mower isnt performng perfectly but was better. The other odd thing was that the manufacturer states that the engine oil capacity is 48 ounces with a filter installed. When I put that much in, the dipstick says that the crankcase is overfilled. I drained and filled last night watching closely. It was full at just over one quart.
 
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Old 05-18-08, 08:42 PM
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After you put the 48 oz of oil in, Did you start the engine & run it @slow idle to fill the oil filter & check for leaks?? If not, it will be overfull because the filter holds a pint or more,,, Roger
 
  #8  
Old 05-19-08, 08:33 PM
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Youd think so but the same label on the inside of the tractor and on the owner's manual state that the fill level for the motor without the oil filter has a capacity of 56 ounces so that difference was supposedly allowed for. Unreal. Thanks for your help.
 
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