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What Should I do when my lawn and garden engine runs rough or has poor idle?


When your gas-powered lawnmower, trimmer or chain saw is running rough or doesn’t idle correctly, the annoying sound is just the start of your problems. When your equipment’s engine isn’t running smooth, performance suffers, leaving the job undone.


If the engine starts, but does not run smoothly, it means that the spark plug and ignition system are in order and you need to look elsewhere for the source of the problem. The usual culprit is air intake or fuel system related.

Hand pulling the starting cord on a lawn mower engine.


Dirty or Clogged Air Filter

The job of the air filter is to remove dirt and debris from the air before it enters your engine. If the filter is doing its job, it may become clogged and not allow a sufficient amount of air into the engine for it to run smoothly, If the filter is dirty, it should be replaced.

Old Gas

When did you last fill up the gas tank? Old gasoline can affect the performance of the engine. Gas can go stale in as little as 30 days. If the fuel is old, it should be dumped into a container for proper disposal and fresh fuel should be added. Other options include adding a fuel stabilizer to your tank or using canned fuel that contains no ethanol.

Obstructed Gas Tank Vent 

After adding new fuel, check the gas cap. In many small engines, the gas cap also has a vent that serves as the fuel tank ventilation. In order to work properly and supply a sufficient amount of fuel to the carburetor, the vent must be open and free of any debris.

Dirty or clogged fuel filter 

A fuel filter that is dirty or clogged with debris can restrict the amount of fuel getting to the carburetor. 



Change air filter if it’s clogged or dirty.


Unclog or replace gas cap if air vent is blocked.


Replace dirty or clogged fuel filter.


Replace old gas with fresh gas (properly dispose of old gas).

If none of these tips get you up and running smoothly, then it’s time to call on a professional mechanic who specializes in small engines. 

Learn more about lawn & garden maintenance products, find your part, or find where to buy your part today.

The content contained in this article is for informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.

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