12 Reasons Why a DeWalt String Trimmer Won’t Start

There are a number of issues that can prevent a DeWalt string trimmer from starting, including a dirty carburetor, a plugged air filter, a faulty spark plug, a faulty starter solenoid, a clogged fuel line, a plugged fuel filter, the incorrect fuel mixture, a broken recoil starter, a plugged spark arrestor, or old fuel.

Continue reading for further potential causes of the beginning trouble you are experiencing.

Before beginning any kind of repair, you should always remove the spark plug boot and wait for all of the components to cease moving.

outdoorstip DeWalt String Trimmer

Causes of the Beginning Issues You’ve Been Experiencing with Your DeWalt String Trimmer

1. Old Gasoline in a DeWalt String Trimmer

When you do not utilize the gasoline immediately and let it linger in your DeWalt string trimmer, this is typically the underlying cause of fuel limits as well as component problems.

After being purchased, gasoline might start to deteriorate as quickly as thirty days later. Ethanol is included in the majority of gasoline offered in today’s market. This is a different kind of fuel that brings water vapor into the gas, and it works very well.

Water and gas do not combine in any way. Instead, the combination of ethanol and water will become gas after it has separated. It is caustic and will leave a varnish left after use.

It is essential to choose a gasoline that has a low percentage of ethanol and to use it up within a month after purchasing it.


After the gasoline that is presently in your string trimmer has been completely depleted, you should replace it with fresh fuel so that it may continue to be utilized. A two-cycle engine requires this mixture of gasoline and oil in order to function properly.

The use of a fuel stabilizer, such as Sea Foam Motor Treatment or STA-BIL, is a smart option when you want to clean out the gasoline system and cut down on the amount of moisture that is there.

2. Improper mixture of oil for a two-cycle engine in a DeWalt string trimmer

For optimal performance, the engine of a DeWalt string trimmer requires a combination of gasoline and engine oil as its fuel. If you use unleaded gasoline in a DeWalt string trimmer with a two-cycle engine, you will cause the engine to freeze up and suffer damage.

Gasoline and oil are combined at a ratio of 50:1 before being injected into a two-cycle DeWalt string trimmer. For example, a 50:1 ratio is 50 parts gasoline to 1 component oil.

Use unleaded gasoline with a minimum octane rating of 89 (mid-grade) and no more than 10% ethanol content when you are preparing the oil and gas combination for your DeWalt string trimmer. This will ensure that the mixture works properly. Including a 2-cycle premium oil that has certifications from both ISO-L-EGD and JASO M345 FD.

Before adding it to your string trimmer, you should first mix it in a gas can that has been certified. Employ an oil designed for two-cycle engines, such as this one made by Kawasaki. This is a 2.6-ounce container that should be mixed with one gallon of gas to achieve a 50:1 ratio.

Gas to oil mixture for the DeWalt 2-Cycle Engine

Mixture1 Gallon Gas2 Gallon Gas2.5 Gallon Gas
50:12.6 oz Oil5.2 oz Oil6.4 oz Oil
32:14.0 oz Oil8.0 oz Oil10.0 oz Oil
Mixture of Gasoline and Oil for the DeWalt Two-Cycle String Trimmer


First, the fuel tank has to be emptied of its contents, and then it should be replenished with the correct mixture of gasoline and oil. If the problem continues, have a technician who specializes in making repairs to tiny engines evaluate it and determine whether or not it can be remedied in a manner that is cost-effective. If the problem continues, the problem has to be rectified.

You may learn more about the sort of gasoline that should be used in your DeWalt string trimmer by clicking on the link provided below.

Premixed Fuel for a Two-Cycle Engine

A fantastic method to minimize the possibility of fuel-related troubles and to boost the lifespan of an engine is to use a gasoline combination that does not contain ethanol. This may be accomplished by using ethanol-free gasoline. This oil and gasoline combination, which does not include any ethanol, may be put into the fuel tank of your string trimmer without any problems.

You won’t need to be worried about the potentially bad effects that ethanol may have because of what was said in the previous section on gasoline. Also, having gasoline that is easily available on your shelf whenever you want it is both useful and convenient to have. TruFuel also provides a nice 50:1 premixed fuel.

3. Plugged Air Filter in a DeWalt String Trimmer

On your DeWalt string trimmer, there is an air filter that serves the purpose of protecting the engine from dirt and other impurities that may do it harm. The air filter has to be cleaned often and replaced once a year at the very least.

When the filter is filthy and clogged with debris, it prevents a sufficient amount of air from passing through it. The engine is unable to start because it does not get the necessary amount of air.

Under no circumstances should you run your string trimmer without the air filter installed, even if you need to run it for a little amount of time to complete a job. If dirt gets into the motor, it may cause excessive wear and tear as well as substantial damage, which may need you to purchase a new string trimmer.

Solution: Remove the filter and clean the housing of the air filter by wiping away any leftover debris using a damp cloth. If the air filter is unclean, you should replace it with a new one.

4. Defective Spark Plug on a DeWalt String Trimmer

Another component of the vehicle that requires regular maintenance is the spark plug. If your engine does not have spark, it will not be able to ignite the gasoline and air that are necessary to start the engine.

It is recommended that this component be changed out once a year to ensure it remains in excellent condition. It is possible for the spark plug to get too dusty, the porcelain to break, or the electrodes to become pitted, all of which will result in the spark plug malfunctioning.


If a filthy spark plug is just somewhat unclean and shows no signs of damage or wear, you may give it a go with a wire brush to see if you can clean it up enough to reuse it. If that is not the case, you need to replace it.

When the mower starts giving me trouble, I like to get a new one simply to be sure that it isn’t a contributing factor in the issue. It is a relatively affordable component, yet it is one of the major elements that ensures your string trimmer continues to function properly.

You need to check that the gap on your spark plug is set according to the manufacturer’s specifications and that the spark plug wire’s boot is fastened firmly. These goods may also have an effect on the beginning of the race.

ModelSpark PlugSpark Plug Gap
DXGST227CSChampion RDJ7J (USA)
Champion QDJ7J (Canada)
.025 in (.635 mm)
DXGST227SSChampion RDJ7J (USA)
Champion QDJ7J (Canada)
.025 in (.635 mm)
The Spark Plug and Electrode Gap for a DeWalt String Trimmer

5. Plugged Fuel Filter in a DeWalt String Trimmer

Inside of the gasoline tank is where you will find the fuel filter. In order to filter the gasoline before it is introduced into the fuel system, it is attached to the fuel line.

Its purpose is to prevent dirt and debris from entering the fuel system of your DeWalt trimmer, which would otherwise cause the lines and carburetor to get clogged and damaged.

When the gasoline filter gets clogged, either because it is not changed out on a regular basis or because you are using the vehicle with particularly filthy fuel, the quantity of fuel that can flow through the filter is decreased. Because of this, your string trimmer may not start, as the engine could not be receiving the gasoline it needs to function properly.

Solution: Within the gasoline tank, you will find the fuel filter that has to be replaced.

  • It is important to remove any loose dirt from the area surrounding the fuel cap before removing the cap from the gasoline tank. Wipe it away with a damp cloth.
  • Get permission to use the filter. To “fish” out the filter and remove it from the tank, a clean wire that has been bent works quite well.
  • It is necessary to remove the old filter from the fuel line. Take cautious not to misplace the retaining ring since it is what keeps the line attached to the filter.
  • After installing the new gasoline filter, be sure to use the retention ring to keep the fuel line attached to the filter.
  • After that, replace the gasoline tank cap and make sure the filter is properly positioned within the tank.

6. Defective Primer Bulb in a DeWalt String Trimmer

If the priming bulb on the DeWalt string trimmer is damaged and won’t take in gasoline, it won’t operate correctly and won’t be able to deliver fuel to the carburetor, which will prohibit the string trimmer from starting. This is because the carburetor needs fuel to function.

Solution: Put in a brand-new priming bulb in its stead.

7. Fuel Line Blocked in a DeWalt String Trimmer

Your string trimmer’s gasoline tank may get clogged with a gummy, sticky residue if you let it sit for a long time if you use old fuel. This might cause the fuel line to get clogged and impede the flow of gasoline, making it difficult for your string trimmer to start.

Solution: If the fuel line on your DeWalt string trimmer has split, kinked, or become clogged, you will need to replace it.

8. Blocked Fuel Tank Vent in a DeWalt String Trimmer

Air may enter the gasoline tank thanks to the vent in the tank. If the fuel tank does not have a vent, a vacuum will be created within the tank, which will prevent gasoline from flowing through the string trimmer.

When your string trimmer runs for a few minutes, then shuts off, and won’t start again until you remove or loosen the fuel cap to allow air into the fuel tank, this is a good indication that you may have a problem with the fuel tank vent. If this happens to you, you may have a fuel tank vent problem.

It is most possible that you have a problem with the fuel vent if, after you have tightened the cap and let the string trimmer to run, it suddenly stops working and won’t start again unless the cap is relaxed.

Solution: It is necessary to replace the fuel tank vent in order to allow air to enter the fuel tank. When it comes to DeWalt string trimmers, the cap is most often where the gasoline tank vent may be found. It is going to be necessary to change the cap.

9. A DeWalt string trimmer with a contaminated carburetor

The carburetor is responsible for controlling the quantity of fuel that is combined with the air in the cylinder prior to the combustion process. The carburetor will get gummed up and clogged with old gasoline, which will prevent it from functioning correctly.

This is an issue that many people face. Since this problem is so widespread, many manufacturers will not honor a carburetor’s guarantee after it has been in use for ninety days.

Solution: If you have any mechanical ability, you should have no problem taking care of the cleaning of your carburetor. Carburetor cleanser should be used after the device has been disassembled and reassembled in order to be cleaned.

If, after being cleaned, the carburetor still does not perform properly, you will either need to repair it or buy a new carburetor to replace it.

10. Poor Recoil Starter on a DeWalt String Trimmer

The motor of your DeWalt string trimmer is started by pulling a recoil starter trigger. Your recoil may not operate properly if you have a faulty pulley, a spring that is too loose or missing, or damaged clips.

Solution: You have the option of replacing the spring and restringing the recoil mechanism. If it does not function because other components in your recoil, such as the clips or the pulley, are broken, it is best to simply replace the recoil assembly rather than trying to repair the individual components.

11. An Issue with the Spark Arrestor on a DeWalt String Trimmer

The spark arrestor that is included in your DeWalt string trimmer has the capability of preventing the device from starting up. A little screen serves as the spark arrestor, and it is susceptible to being clogged with soot.

Solution: Ensure that the spark plug boot is disconnected. Check to see that the engine is not too hot. Take off the engine cover as well as the lid for the engine exhaust.

Take out the spark arrestor, clean it with a wire brush, and then put it back in place to get rid of the soot. If you are unable to clean it to an acceptable level, if it is damaged or has a hole in it, you should get a new spark arrestor and use it instead.

12. Flooded DeWalt String Trimmer

Clients who tried to start their string trimmers on their own were unsuccessful, so they took them to a service that specializes in string trimmer repair. The flooded engine is often to blame for the issue, which is not a very serious one.

It is possible for the engine to get flooded if the choke is set to the closed position, the starting rope has been pulled many times, and this allows an excessive amount of fuel to enter the carburetor. While the choke is in the closed position, this occurrence takes place.

In addition, it is possible for it to occur when the switch is off, the beginning rope is pulled several times, and the priming bulb is pushed an excessive number of times. Finally, it is possible for it to occur when the switch is off and the starting rope is pulled numerous times.

Solution: Follow the steps below to “unflood” your string trimmer and ensure that the engine receives the ideal ratio of gasoline to air that is necessary for it to start and continue operating.

Fixing a Flooded Engine on a DeWalt String Trimmer and Other Devices

  • The choke lever has to be moved to the run position.
  • When you repeatedly pull on the starting rope, press the throttle trigger lockout and make adjustments to the throttle control. The number of pulls required to get this going might range anywhere from 5 to 15. The engine of your string trimmer will start to splutter initially. Keep pulling it and give it a couple more tries; it ought to start now.