You grab your trusty weed-eater to get started on that overgrown grass that’s been put off for weeks. It starts up just like normal, but there is one problem. Each time you press the throttle the engine bogs down, shut off, or perhaps won’t even start. This could be one of several issues or maybe a combination. Though it may seem like a frustrating situation, you might wanna hold off on taking it to the repair shop.


In this article, I’ll be outlining a few common problems that may cause your weed whacker to bog down and possible solutions. These solutions should not take long and require little knowledge of small engine repair.

Clogged up spark arrestor

Dirty spark arrestor Stihl FPS 200

The spark arrestor is a wire mesh type material normally found on the end of your muffler and in some cases, it is screwed in. These screens sometimes tend to get clogged up with carbon and as a result, stops exhaust from properly exiting the motor. When this happens your motor will likely have issues running properly.

  • Scrub away any buildup using a wire brush or burn it off with a torch if you have one. These are just a few methods, but you can try whatever works best for you. Some professionals remove the spark arrestor completely from the unit itself because they believe it is not vital. I however tend to play it safe and keep all parts intact as the manufacture intended.

Dirty Air filter

Stihl fs200 air filter

Like the arrestor, a clogged-up filter can cause your engine to not function properly. Most air filters are located within an easily accessible area of your engine. You probably won’t need any tools to remove the air filter on most weed-eater models. Carefully remove and inspect the condition of the air filter is in.

  • Replace the air filter if it is extremely dirty or carefully scrub off as much buildup as possible using a brush. A solution of soap and warm water can be used to clean off some of the excess oils if needed.

Dirty spark plugs

Stihl FPS 200 spark plug

Sometimes the spark plug may just need to be cleaned or replaced after extended usage. In most scenarios, your weed whacker will run rough or refuse to start periods if the spark plug is dirty.

  • Remove the spark plug and inspect it for build-up. Use a wire brush to carefully scrub away any dirt from the spark plug.

Fuel not circulating properly

Stihl fs200 fuel filter

Although this may seem obvious to many, the problem could be something simple as an empty fuel tank or bad gas. If you’re sure it’s none of these then the next step would be checking for any damaged or disconnected fuel lines. Lastly, inspect the fuel filter located in the tank to see if the gas is circulating properly.

Fuel filters stop most of the larger unwanted sediment and other debris from entering the carburetor. For various reasons, these sediments may enter the gas tank and eventually clog up the fuel filter. When this happens this may restrict the proper flow of gas when you press the throttle.

  • Carefully remove and store any gas from the tank. With the tank empty you should be able to have a clear view of the fuel filter. Replace the fuel filter if it is clogged up. When refilling the tank make sure that you are not pouring dirty gas back into the tank.


If after cycling through all these scenarios your engine continues to bog down or shuts off then you may have to take some time to further diagnose the issue. There could be a range of different problems such as a gummed-up carburetor, a carburetor that needs adjusting, low compression, or a bad ignition coil. You can take a look at my article “common small engine problems”, which further explains many of these issues.

Lastly, it is recommended to always have a cheap maintenance kit in storage. These kits should be available at your local hardware store or most major online retailers like Amazon. When purchasing a kit always read the description to make sure it is compatible with your weed eater.

A good kit should have basic parts such as an air filter, spark plug, primer bulb, and fuel line. For a few extra dollars, you can purchase a kit that has a carburetor. Your user manual will give you a general idea of when to perform general maintenance.