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Help! Why Won’t My Weed Eater Start?

We’ve all been there- we store away our string trimmer at the end of the growing season and when it comes time to fire it up again in the spring, the darn thing won’t start.  In my household it’s cause for a fair amount of frustration, prayers to the lawn gods, and the occasional expletive each spring as I prep, prime, and attempt to get items that have been stored for months started again.

But what’s even more frustrating is when your weed trimmer has been working just fine and then, simply put: the weed eater won’t start. No matter the circumstances, before you load it up for a trip to the hardware store, look over the following helpful hints that might just get you back up and running fairly quickly- and save you both time and money. Most weed wackers, whether handheld or walk-behind, are simple enough in their design to troubleshoot fairly easily.

Fuel Issues

gasolineAssuming your gas is topped off (don’t laugh, empty gas tanks happen to the best of us), make sure you have mixed fresh fuel with the correct ratio of 2-cycle oil (40:1, or 1 gallon fuel to 3.2 ounces oil), or you run the risk of seizing up the engine over time. Your fuel should also be less than 90 days old, as it might not move fluidly through the carburetor to the spark plug and fuel filters can more quickly become clogged as well (although clogged fuel filters are a rarity).

If all of the above is set, remember that oil and gasoline separate over time and it is recommended that you shake your mixed fuel before topping of your tank. Also swishing around the existing fuel in the tank before getting started ensures that not just straight gasoline or oil is primed through the carburetor.

Attempting to start your engine too many times, or turning your trimmer on it’s side, can also resulted in a flooded engine. If you think this might be the case – set your choke lever to ‘run’ and pull the cord to burn off the excess fuel. You may also need to allow your weed wacker to rest for 10 to 15 minutes before trying to start again.

Air Filter Blockage


If you engine is trying to run, or starts and quickly stops, you might want to do a quick air filters check. Like all things with an engine, you need air for your initial spark- and if oxygen cannot move readily through the system you will have problems both starting and keeping your weed eater running.

Your air filter is there to do just that, filter the air, so it makes sense that sometimes this does get grimy and blocked up. Cleaning, or replacing, an air filter is incredibly simple and straightforward.

To see just how simple, watch below:


Spark Plug Malfunctions

warningEven with poorly mixed fuel and dirty air filter, you should get some sort of response from the engine. If you don’t even get a half-hearted splutter, then the problem may lay with your spark plug. Dirty spark plugs are a common problem and will hinder the ‘spark’ that helps fire up an engine. Luckily, this is a simply fix, and by removing the plug and cleaning it with a wire brush and a little gasoline- you may solve well over half your starting issues.

Once you have the spark plug removed, look it over carefully for cracks in the ceramic, and check the gap as well. If your plug has a crack, you need to get a new one as the spark isn’t going to make the jump to get started. The same goes for the gap. The gap between the plug nodules should measure .025” to .030” and anything larger, or smaller could be causing you issues and needs to be adjusted or replaced.

Spark plugs are very inexpensive and if you have taken all these precautions, or even replaced your plug, then you might have a bit more of a complicated problem that requires a little more knowledge of where parts are located on your model.
If you need help removing your spark plug, watch below for some quick, handy tips:


The carburetor is the heart of an engine’s starting mechanism, and if something goes wrong with it, then it’s going to be pretty hard to get your weed wacker started. If you have a primer button, this is what it is located on, and it sprays fuel into the reservoirs that help your spark plug fire up the engine.

A lot of the time your carburetor may just need a thorough cleaning to get rid of the dust and grime that has built up around it and in it over the years. This process may also include having to replace it since once you take it off you may find it looking amiss. In my case, a small piece of plastic housing had broken loose and had actually lodged into the carburetor, calling for a new one.

Occasionally only the primer bulb weathers and cracks or breaks as well, and these are simple and cheap to replace.

Whole Carburetor replacements are fairly inexpensive and are worth the purchase rather than setting out to replace the entire weed eater itself.

For a step by step removal and cleaning guide, watch below:

Electrical and Battery Problems

If you have an electrical weed trimmer, then the most obvious troubleshooting is where you need to start: the power source. Check that all electric cords are plugged in securely, and that the electrical outlet itself is drawing power. Do this also for battery powered trimmers where the charge occurred and that the charger is also working correctly.

Also check your fuses and circuit breaker to make sure no problems exist with the power source.  
Extension cords can also become faulty over time, and if they do not have a light check built in, you might want to test the weed wacker with another cord to rule this out.

Time to Fire It Up!

Hopefully the above information has allowed you to get back to work using your weed wacker around the yard, or at the very least narrowed down what might exactly be the problem. If you have found any other suggestions to help solve this problem, or have any questions, please comment below. And as always, share and save this page for future reference!

Remember to check for:

Gas tank and fuel ratio
Mix it up!
Clean air filters
Get rid of dust!
Spark plug cleaning or replacement
Check the gap!
Primer bulb
Any cracks?
Carburetor cleaning or replacement
Clean out the grime!
Electrical sources and cords
Do you have power?

About The Author

Danielle McLeod

Danielle McLeod cuts a tragic figure in the High School English classroom teaching literature by day, and moonlighting as a writer and graphic artist by night. Published in a variety of travel magazines, and now a blog, Danielle enjoys coming up with home and garden projects to complete with her two young boys. A native of Michigan, she resides in Southeastern New Mexico with her variety of horses, poultry, and variable mix of rescue dogs (there’s a cat or two in there as well). In her free time she enjoys travel, art, photography, and a good book!


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