How to Troubleshoot a Toro String Trimmer

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You can troubleshoot a string trimmer.
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A Toro string trimmer adds definition to your landscape not only by cutting weeds but also by tidying scraggly edges around your lawn, flower beds and other structures. When it won't start or otherwise experiences problems, working through a few troubleshooting steps can help you diagnose the problem and find the solution for restoring your Toro to trimming mode. Before you think the worst — that there's a major problem with your string trimmer — it may be comforting to know that most issues are easily resolved with a little DIY tweaking.


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Before operating, maintaining or repairing your string trimmer, observe all safety precautions outlined in your user manual. Be sure to wear protective equipment, including eye protection (eyeglasses or safety glasses), rubber gloves and long pants. If you have an electric trimmer, don't forget to unplug it before making any adjustments, replacing any parts or repairing it.

Troubleshooting the Battery Pack and Filters

When something prevents the transfer of power from the power source to the working parts of a Toro string trimmer, where you'll target your troubleshooting depends on what type of trimmer you have. If you have a cordless trimmer that won't start, check to make sure that the battery pack is fully charged and that it's properly locked in place. You may need to replace the battery pack if it no longer works.


If you have a gas-powered trimmer, check the air filter and the fuel filter. Both of these components can become clogged over time, which causes the trimmer to operate sporadically or not to start at all. If the air filter is clogged, you'll need to replace it. If the fuel filter is clogged, drain the old fuel from the tank, clean the filter and put it back in place. You may need to replace an old fuel filter if draining the old fuel and cleaning the filter doesn't work.

Troubleshooting the Carburetor

Old fuel left in the trimmer's tank may partially evaporate, leaving a sticky substance that clogs the carburetor, eventually preventing the trimmer from starting. Instead of replacing the carburetor as a first measure, try cleaning it with a carburetor cleaner. Always draining the fuel at the end of the season is part of the proper way to store a string trimmer. You may also need to adjust the carburetor according to the directions in your user manual.


Troubleshooting the Spark Plug and Spark Arrestor

If you suspect your trimmer may have a faulty spark plug, use a spark plug tester to find out if it's defective. When you try to start the trimmer, the tester should show a strong spark between the terminals on the tester. Sometimes, you'll be able to observe obvious signs of damage without even using a tester, including cracks to the porcelain insulator or a burned electrode, which shows signs of black carbon buildup.

A spark arrestor is a different part from the actual spark plug. It's the small screen that doesn't allow the engine to emit sparks, but over time and after many starts, the spark arrestor becomes clogged with soot. This can prevent the string trimmer from starting. A simple fix is to remove the spark arrestor and clean the screen with a wire brush, but you can also replace this part.


Whenever you replace any part on a Toro string trimmer, be sure to only use replacement parts that are factory-approved. Otherwise, you may void your warranty if you use nonapproved parts.



Victoria Lee Blackstone is a horticulturist and a professional writer who has authored research-based scientific/technical papers, horticultural articles, and magazine and newspaper columns. Her writing expertise covers diverse industries, including horticulture, home maintenance and DIY projects, banking, finance, law and tax. Blackstone has written more than 2,000 published works for newspapers, magazines, online publications and individual clients.