4 Cycle Trimmer Motor dies when trottled

ccbadd

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Jun 23, 2013
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I have a 4 cycle craftsman trimmer purchased about 6 years ago. I recently had trouble getting it to start. I replaced the fuel line, fuel filter, and gas as I have had to do in the past but it did not work this time. I then replaced the carb. Still would not start so I replaced the spark plug. Now it will start and idle just fine but as soon as I give it some throttle it dies. I read around and some mentioned the possibility of the gas cap vent being plugged so I replaced it this morning. Same problem. Any ideas of what to check next?
 

ccbadd

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Well I finally got fed up and decided to start looking for a new trimmer. While I was looking I found two more things to check. First was cleaning the spark arrestor screen. I pulled it off and cleaned it even though it didn't look very bad at all but still no go. The last thing I found was a youtube video on setting the gap on the valves. The intake valve was indeed loose so I got out the old feeler gauges to set the gap but had a hard time. I decided to pull the valve cover off and set the gap while running and sure enough my trimmer is running like a champ again! I just tightened it down until the engine died and then backed off a bout a half turn.
 

motoman

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What is plug color. Intake has leak(?) which coupled with open butterfly puts mix strength below firing threshold? If so would expect very light to white to no color plugs. In brand new Craftsman I had a push on breather not connected to intake nipple , etc. Float or fuel level low due to resitriced line, plugged filter?
 
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