9 Causes Of A DeWalt String Trimmer’s Rough Performance

The motor on your string trimmer seems to be functioning normally. When you pull the throttle lever, it loses speed and bogs down.

If your DeWalt string trimmer is making funny noises and struggling to get going, check for the following: low quality gasoline; a dirty carburetor; a clogged fuel line; a stopped fuel filter; a dirty spark plug; a clogged fuel tank vent; a clogged air filter; or a clogged spark arrestor screen.

If you want to prevent getting hurt when fixing your string trimmer, make sure to follow all of the safety guidelines listed in the owner’s manual. To do so, turn off the engine and wait for all moving parts to halt before disconnecting the spark plug wire.

string trimmer

8 Causes Of The Rough Performance Of Your DeWalt String Trimmer.

DeWalt String Trimmer with Old or Bad Fuel

If your DeWalt string trimmer isn’t working as well as usual, try filling the gas tank. Since gas oxidizes and decomposes with passage of time, this occurs.

Today, most gasoline on the market contains ethanol. Due to its hygroscopic nature, this alternative fuel draws atmospheric moisture into the fuel injection system. A DeWalt engine could bog down or run rough as a result of this.

Besides being detrimental to the fuel system and the engine, the varnish left behind by this water and ethanol mixture causes fuel limits.

Proper fuel selection and timely use are critical to engine performance.

When deciding what kind of gasoline to use in your DeWalt string trimmer, keep the following in mind:

  • Get new unleaded gas with an octane value of 89 or higher and no more than 10% ethanol added.
  • Two-stroke motors necessitate a 50:1 2-cycle oil mixture. Before putting it to the fuel tank, combine gasoline and 2-cycle engine oil.
  • The fuel must be used within 30 days.
  • If you won’t be using the fuel within 30 days, you can extend its shelf life by adding a fuel stabilizer.
  • Keep gasoline and other fuels inside a fireproof building, far from anything that could catch fire.

A WAY OUT: Get rid of the stale gas in the tank. String trimmer fuel is stabilized, the fuel system is cleaned, and moisture is reduced when you mix in a fuel stabilizer, such as Sea Foam Motor Treatment or STA-BIL.

Fill the gasoline tank with the treated fuel mixture and start the engine. Let it run for 5 minutes to let the fresh fuel circulate through the system. There’s hope that the DeWalt string trimmer will start performing better.

If it doesn’t work, go down the list until you discover what does.

DeWalt String Trimmer with Clogged Fuel Filter

Keep looking for other potential fuel limitation causes. Be sure to check the fuel filter. There is a tiny cylinder-shaped piece like this attached to the fuel line inside the fuel tank.

Failure to replace the filter on a regular basis can prevent clean fuel from reaching the carburetor. The trimmer’s performance will suffer as a result.

Here’s how to change a clogged fuel filter in a DeWalt tool:

  • Arrange the trimmer in a horizontal position.
  • Remove the fuel cap and wipe the area around it to get rid of any dirt.
  • Make sure you remember where the gasoline filter is so you can replace it properly.
  • Get a clean, bent wire and use it to pry the fuel filter out of the tank.
  • Grasp the fuel line firmly, then take the filter out of the fuel line.
  • Replace the old fuel filter with a new one.
  • Reinstall the fuel tank filter within the tank.

DeWalt String Trimmer with Blocked Fuel Line

Check the gasoline line for any obstructions or kinks that might be preventing fuel from flowing freely. This is because unclean fuel or sticky residues left behind by running old fuel might cause blockages.

When you notice a clog, kink, puncture, or leak in your DeWalt line, the solution is to replace it with a brand new gasoline line.

Unclean DeWalt String Trimmer Carburetor

So that the DeWalt can be started and maintained, the carburetor controls how much fuel is blended with air for combustion.

If the string trimmer’s fuel-to-air ratio is off, its performance may suffer. Clogging of the carburetor’s passages and sticking of its many minute parts are also possible.

A rough-running engine may be the result of the DeWalt carburetor’s inability to provide sufficient gasoline.

You may try cleaning the carburetor to see if it helps. If cleaning the carburetor doesn’t fix the problem, you may need to rebuild it (if rebuild kits are available for your carburetor model) or replace it.

Carburetors often break when contaminated fuel is forced through them.

Use new fuel to protect the carburetor as much as possible. Use a non-ethanol fuel, such as TruFuel 50:1 Premix for 2-cycle engines, to keep the carburetor from corroding from contact with ethanol.

DeWalt String Trimmer with a Grimy Spark Plug

If your DeWalt trimmer is misfiring and running slowly, check the spark plug.

Another cause of your string trimmer not starting could be a damaged spark plug, an improper spark plug gap, or a loose spark plug wire.

Use a socket wrench to take out the spark plug. Investigate its state of repair. If the spark plug’s tip is very dark, the porcelain is fractured, or the electrode is burned, you should replace it.

The spark plug can be cleaned with a wire brush or swapped out for a new one if inspection reveals it is otherwise functional but simply dusty.

Using a feeler gauge, verify that the spark plug gap satisfies the criteria set forth by the engine manufacturer. Change out or clean the spark plug and install it. Check that the spark plug wire is properly attached.

DeWalt String Trimmer with Blocked Fuel Tank Vent

While fuel is being used, air must be able to enter the tank through vents in the fuel tank. A good deal of fuel won’t reach the carburetor if the vent is blocked.

Because of this, the engine will sputter and stall.

DeWalt string trimmers have a fuel tank vent, which is either a small piece of hardware at the end of a line leading from the fuel tank or an integral element of the gasoline cap.

If the gasoline pump isn’t working and there isn’t a blockage in the fuel line, fuel filter, or carburetor, the fuel tank vent may be clogged.

A vacuum can indicate a blocked fuel tank vent, which can be checked with a pressure gauge. A running test with and without a snug fuel cap might reveal whether or not the tank vent is blocked in the absence of a gauge.

As a first step, you should crack open the gasoline cap and let some air into the tank. Kick on the trimmer and let it go. If you don’t want to waste gas and have to refill the tank, be mindful and maintain the string trimmer on a flat surface.

You can prove the fuel tank vent is faulty by repeating the problem and observing whether or not the DeWalt trimmer bogs down or runs rough after tightening the fuel lid.

If, after returning the fuel cap, your trimmer continues to act up and run roughly, the problem is likely the fuel tank vent, which may be easily replaced.

DeWalt String Trimmer with Blocked Air Filter

A DeWalt string trimmer won’t start without an air filter. It safeguards the motor by preventing debris from entering the air intake.

If you don’t inspect, clean, and change your trimmer’s air filter regularly, it will get clogged with dirt and prevent enough air from reaching the engine.

If there isn’t enough air, the motor will sputter and stall. Keep the air clean so the engine doesn’t overheat from a lack of oxygen.

If the air filter is in good shape, clean it as described below for a foam air filter. A new filter should be installed if the old one is severely clogged or broken.

For information on how to clean a filter of a different design, please refer to the manual that came with your machine.

How to maintain a clean air filter for a DeWalt FOAM string trimmer:

  • Take off the air filter and its housing.
  • You can use water and a mild detergent to clean the foam air filter.
  • Let the filter air dry after rinsing it with clean water until the water is clear.
  • When the filter is dry, use SAE 30 motor oil to lightly saturate it. Remove any lingering oil by gently squeezing the filter.
  • Get the filter back in place.
  • Put back the air filter cover.

The DeWalt String Trimmer’s Plugged Spark Arrestor

A DeWalt string trimmer’s thin metal screen prevents harm or fire from hot exhaust material blasting out of the machine. Over time, carbon buildup will prevent air from passing through this tiny screen, which will negatively impact the performance of the engine.

Ignition wire, please. Take off the engine cover and the exhaust cover. With a metal brush, carefully remove the spark arrestor screen.

Put in the new spark-proof screen after cleaning it. Connect the exhaust cover back to the engine and replace the engine cover. To reconnect the spark plug wire, please.

A new spark arrestor screen must be installed if the old one is too dirty, broken, or has a hole in it to be repaired.

Adjusting DeWalt String Trimmer Carburetors

Changing the RPMs at idle and full throttle may require adjusting the carburetor. The trimmer’s harsh operation could be due to the engine running too lean or too rich.

There are screws on the carburetor for making modifications like these, but you’ll probably need a specialized tool.

If the above-mentioned solutions don’t work, take the trimmer to a local DeWalt service center and have them check the fuel and make any required modifications to the carburetor. The engine can be damaged irreparably if the carburetor is over-tweaked.