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HomeRepair HelpCraftsman Mower RepairCraftsman Lawn mower runs rough Repair
Craftsman Lawn mower runs rough
If your Craftsman lawn mower runs rough, sputters, or the engine runs unevenly after starting, the carburetor is the first place to look. Old fuel often leaves behind a sticky varnish that clogs the carburetor, which is the most common reason a lawn mower runs rough or starts to surge. Try cleaning the carburetor with carburetor cleaner first. If that does not fix it, a carburetor repair kit or a full carburetor replacement is usually the next step. After that, check the spark plug for heavy carbon buildup, a cracked insulator, or a damaged electrode, and use a spark plug tester to confirm it is producing a strong spark while the engine is cranking. A weak or failed plug can also cause lawn mower sputtering and rough operation. If the mower still runs poorly, inspect the fuel filter, since old fuel can clog that part too and restrict fuel flow enough to make the engine stumble. To get the exact Craftsman replacement part that fits your mower, enter your model number on RepairClinic.com.
01 - Craftsman Lawn Mower Carburetor
The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the lawn mower for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and cause the engine to run roughly. If the carburetor is clogged, try cleaning it with carburetor cleaner. If cleaning the carburetor isn’t effective, rebuild or replace the entire carburetor.
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02 - Craftsman Lawn Mower Carburetor Repair Kit
The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the lawn mower for a long period of time. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the carburetor and cause the engine to run roughly. If the carburetor is clogged, try cleaning it with carburetor cleaner. If cleaning the carburetor isn’t effective, rebuild or replace the entire carburetor.
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03 - Craftsman Lawn Mower Spark Plug
Inspect the spark plug for signs of wear or damage. If the porcelain insulator is cracked, an electrode is burned away or damaged, or there is heavy carbon buildup at the electrode, replace the spark plug. To determine if the spark plug is defective, use a spark plug tester. You should see a strong spark between the tester’s terminals when the engine is cranking. If there is no spark, this indicates that the spark plug is defective and should be replaced.
Highly Likely
04 - Craftsman Lawn Mower Fuel Filter
The fuel filter might be clogged. A clogged fuel filter is most commonly caused by leaving old fuel in the lawn mower. Over time, some of the ingredients in the fuel may evaporate, leaving behind a thicker, stickier substance. This sticky fuel can clog up the fuel filter and cause the engine to run roughly. If old fuel was left in the lawn mower, drain the old fuel from the fuel tank and replace the fuel filter.
Less Common
Frequently Asked Questions
Why does my Craftsman lawn mower run rough after it starts?
Can a bad spark plug make a Craftsman mower run rough?
Will a clogged fuel filter cause my Craftsman lawn mower to sputter or surge?
Should I clean, rebuild, or replace the carburetor on my Craftsman mower?
How do I find the right carburetor, spark plug, or fuel filter for my Craftsman lawn mower?
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