Why Does My Hedge Trimmer Keep Stopping?

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Is your hedge trimmer always stalling? Maybe you can get the tool to start but then it suddenly stops, or the engine sounds rough. There are many possible reasons why this can happen. In this article you will learn the most likely reasons and how to fix it.

Low battery power is the most common reason why cordless hedge trimmers start and stall. If yours is electric, ensure it is securely plugged in the power source. A clogged carburetor will cause gas hedge trimmer engines to idle and stop.

There are three basic types of hedge trimmers: electric, gas and cordless (battery). They may stall or start/stop for different reasons and we will look at all of them here.

Dirty or Damaged Blade

Hedge trimmer blades accumulate dirt and debris, and over time this can slow performance. A blade clogged with dirt or tree sap is going to have a hard time cutting, if it moves at all. If the blade is dirty, cleaning is required. If the blade has dulled you have to sharpen it, but if there is damage, replacement is needed.

Turn your hedge trimmer off. Unplug the cord (if it is electric) and remove the blade from the main trimmer body. You may need a screwdriver to do this. Once the blade is removed, wipe it with a wet rag. Use soapy water to remove the dirt and rinse with water.

Examine the blade. Are there signs of damage anywhere? Are there missing teeth, chipping, dents etc.? Replace the blade if you see any damage. This video shows you how it is done.

If the blade is not damaged, check if it is still sharp. Sharpen the blade if required. If it is still usable, give it a good cleaning and apply lubricant. Put the blade back on and try the hedge trimmer again. Usually cleaning, sharpening or replacing the blade works. If not, try the following solutions below.

Overheated Motor Engine

Hedge trimmer motor engines will overheat for various reasons. Lack of lubrication, overworked, the temperature is too high and mechanical failure are the most likely causes. Using a quality product such as the Black + Decker BEHT100 means less worry.

Lubrication cools the engine and can prevent overheating. When a hedge trimmer runs, its motor engine is constantly moving. This generates friction which produces heat. If the engine is not lubricated, the temperature will go up rapidly.

If you are using the hedge trimmer to cut thick branches in hot conditions, the engine will eventually overheat and stall. Turn the hedger off and wait for the motor to cool down. When it does, check the engine for signs of damage. If there is none, clean it thoroughly.

Dirty Air Filter

The air filter on your hedge trimmer prevents debris from getting into the motor while allowing clean air through. With constant use, the air filter gets clogged with debris. Some of these end up inside the engine, and clean air cannot get in. Under these conditions the engine temperature increases and leads to overheating. The solution is to clean or replace the air filter.

To do this, remove the cover. Depending on your hedge trimmer you may have to remove some screws or just pry if off. After you lift the cover you can clean the air filter or replace it.

You should do this regularly for the best performance. How often varies from case to case. Inspect the air filter after each use and clean it. At the very least you should do this once a week. Replace the air filter if it has gotten too clogged.

Dirty Fuel Line

The fuel line in your hedge trimmer has to be kept clean, otherwise the engine could halt. If the fuel line is blocked there is no way for the gas to reach the engine. Without gas there is no way for your hedge trimmer to run.

To remove any clogging, lift the line off the fuel tank and carburetor. Look for signs of clogging. If there is, replace the line. Sometimes you may have to blow at the line to test for blockages. In any event, you have to replace the fuel line. Not doing so will prevent fuel or limit the amount of if getting into the engine. This is true for almost all gas hedge trimmers including the Dewalt DCHT820B.

Clogged Fuel Filter

The fuel filter prevents dirt from clogging up the motor. Just like air filters, the fuel filter gets blocked eventually. Unlike air filters which can be cleaned, a clogged fuel filter needs to be replaced.

The filter can be found on the fuel line which is linked to the fuel tank. By looking at the filter you should be able to tell if it is clogged or not. Replace the filter and the motor should cease stalling.

Fuel filters should last a long time, but it will also depend on how you use your hedge trimmer and the kind of environment it is exposed to. A heavily used gas trimmer will end up with a clogged fuel filter faster than a rarely used one.

Low Battery Power

A cordless hedge trimmer will cease running when the battery is very low. In some cases the trimmer will cease functioning before the battery goes empty. When power is close to empty there won’t be enough energy to keep the tool running.

If your hedge trimmer stops or the motor is struggling, it might be running low on battery power. Check the status and recharge if needed.

Manufacturers provide a runtime, but those are under ideal or normal conditions. A cordless hedge trimmer might have a running time of 2 hours, but that assumes the tool is used regularly. If you cut thick branches or hedges, it will use up power quickly.

Make sure your hedge trimmer is fully charged before using it. If the battery is not charging, there could be a problem with the charger or the power source. Try another outlet and another charger if possible. If both are working it is the battery itself that needs replacement.

Carburetor Problems

There are two issues that you might encounter here, clogging or a wrong configuration. Either way you have to open up your hedge trimmer to access the carburetor. In most hedge trimmers you have to remove the air filter before you can get to the carburetor.

The first thing you should do is check if it is clogged. A dirty carburetor is easy to spot so give it a good cleaning. There are cleaning solutions available that you can use.

Another thing you can do is adjust the carburetor settings. Look for adjustment screws and change the configuration incrementally. If the screws are not done properly, air will not get in the motor, which can lead to stalling.

Some carburetors also have idle adjustment screws, labeled L (low) and H (high). Shut both screws off then turn them but in the opposing direction twice. Turn the engine on and allow the motor to idle for a minute.

Adjust the L screw clockwise to idle. Go to full throttle and turn the H screw to clockwise. Note that some carburetors do not have idle or adjustment screws. In that case the only option is to clean or replace the carburetor.

Electric Hedge Trimmer Issues

There are many reasons why your tool may be stalling.

  • Overheated motor. Shut the motor off and allow it to cool down. Clean the motor, air intake and other parts.
  • Blade is not moving. Check for signs of damage and if there is, replace it. Sharpen the blade if it has dulled. Remove any clogging or dirt buildup.
  • Trigger switch is broken. Take the trimmer to a service repair center to have the switch replaced.
  • No power. Check the power source and the cord. Make sure it is plugged in tight.

If you are using an electric hedge trimmer, make certain it is securely plugged in. Do not use the trimmer if the cord has frayed or shows other signs of damage.