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HomeRepair HelpMTD Small Engine RepairMTD Small engine runs poorly Repair
MTD Small engine runs poorly
If your MTD small engine runs poorly, runs rough, sputters, surges, or loses power, the carburetor is the most likely cause. A clogged carburetor can restrict fuel flow and prevent the correct air-fuel mixture, especially when stale or ethanol-blended fuel has been left in the carburetor during seasonal storage. Clean the carburetor with carburetor cleaner first. If the blockage remains, rebuild it with an MTD small engine carburetor repair kit or replace the carburetor. Next, inspect the spark plug for a cracked insulator, burned electrode, or heavy carbon buildup. Test it with a spark plug tester and replace it if it does not produce a strong spark while the engine is cranking. A clogged fuel filter is another possible cause of an engine running rough, particularly after old fuel has been stored in the fuel tank. Drain the old fuel and replace the fuel filter. Enter your model number to find the exact replacement carburetor, repair kit, spark plug, or fuel filter for your specific MTD engine.
01 - MTD Small Engine Carburetor
The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the engine 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 - MTD Small Engine Carburetor Repair Kit
The carburetor might be clogged. A clogged carburetor is most commonly caused by leaving fuel in the engine 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 - MTD Small Engine 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 - MTD Small Engine Fuel Filter
The fuel filter might be clogged. A clogged fuel filter is most commonly caused by leaving fuel in the engine 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 fuel filter and cause the engine to run roughly. If old fuel was left in the engine, drain the old fuel from the fuel tank and replace the fuel filter.
Less Common
Frequently Asked Questions
Why is my MTD small engine running rough or surging?
Can old gas make an MTD small engine run poorly?
How do I test the spark plug on an MTD small engine?
How do I find the correct carburetor, fuel filter, or spark plug for my MTD small engine?
What should I check before taking apart an MTD small engine that runs poorly?
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