Unlock the Right Part
for Your Repair
Find the exact part you need
Enter your model number to see parts that fit your machine.
Choose Product
Identify Problem
03
Find Solutions
HomeRepair HelpSimplicity RepairSimplicity Lawn mower runs rough Repair
Simplicity Lawn mower runs rough
If your Simplicity lawn mower runs rough, sputters, or the mower engine runs unevenly after starting, the most likely problem is a clogged carburetor caused by old fuel left sitting in the tank. As fuel breaks down, it leaves a sticky residue that can block passages in the carburetor and make a lawn mower run rough or surge. Start by cleaning the carburetor with carburetor cleaner. If that does not help, rebuild it with a carburetor repair kit or replace the carburetor altogether. Next, check the spark plug for a cracked insulator, burned electrode, or heavy carbon buildup. A weak or failed plug can also cause lawn mower sputtering, and a spark plug tester will tell you if the plug is producing a strong spark while the engine is cranking. If the plug checks out, inspect the fuel filter, since a partially clogged filter can restrict fuel flow and cause the engine to run rough. Drain stale fuel if needed. Enter your Simplicity model number on RepairClinic.com to find the exact carburetor, carburetor repair kit, spark plug, fuel filter, or other replacement part that fits your mower.
01 - Simplicity 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.
Enter model number to search for the required part specific to your product
Top Solution
02 - Simplicity 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.
Top Solution
03 - Simplicity 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 - Simplicity 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 Simplicity lawn mower run rough after starting?
How do I know if the carburetor is causing my Simplicity mower engine to surge or sputter?
Can a bad spark plug make a Simplicity lawn mower run rough?
Will a clogged fuel filter make my Simplicity mower sputter or run unevenly?
How do I find the right carburetor, spark plug, or fuel filter for my Simplicity lawn mower?