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Stalling lawm mower with blackened spark plug

Posted by packard53 WA (My Page) on
Fri, Jul 23, 10 at 21:27

I have a mower with a Briggs and Stratton Q 4.5 engine that's given good service over the past 5 years. Recently, it started surging / lagging after about 5 minutes or so of use; it starts up fine and runs well initially. I replaced the carb spring, cleaned the air cleaner, cleaned out the gas tank and filter. When I removed the spark plug, it had thick black deposits. I replaced the plug, but after running for only about 20 minutes, it also had lots of thick black soot on it. It's behaving like it's not getting enough air / running too rich, but I don't know what else to do. Suggestions? Thanks.


Follow-Up Postings:

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RE: Stalling lawm mower with blackened spark plug

Try replacing rather than cleaning the air filter if it is paper.


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