Hedge Trimmer Won’t Stay Running Solved

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You turn on your hedge trimmer and hear the familiar sound of its motor. Suddenly it halts and refuses to run anymore. Is the engine dead? Do you need to take it to a specialist? In most cases the answer is no. There are many reasons why this happens and here you will learn how to fix it. And as will be clear, you can do the repair on your own.

A blocked air filter or faulty spark arrestor can cause a hedge trimmer to start and stall. Another possible reason is old fuel stuck in the carburetor. Months-old fuel leaves a thick, gooey residue that can clog the carburetor and engine.

Clogged Carburetor

The most common reason why hedge trimmers won’t stay running is old fuel. You should change the fuel every 30 days because over time, it dissipates and leaves behind a sticky material. This sludge ends up all over the carburetor and the rest of the engine. Problems with the carburetor can also be the reason why your hedge trimmer keeps stopping.

The residue makes it hard for fuel to reach the carburetor. If there is not enough fuel, the hedge trimmer will not be able to sustain its power. This is why the trimmer starts and suddenly stops.

Solution. Clean the carburetor.

Turn the hedge trimmer off. Refer to the owner’s manual to find the carburetor. You might have to remove a casing covering it. When you see the carburetor, it will likely be covered in old, sticky oil.

Use a carburetor cleaning solution to remove the residue. The Ultrasonic Cleaner cleans not only the carburetor but also other engine components

Wipe the rest of the engine and anywhere else the sticky stuff spread to. Drain whatever oil is left.

Clean the fuel tank and pour a gas oil mix. The ratio is usually 40:1 but yours might be different so check the manual.

Turn the trimmer on and let it idle for a few minutes. If it does not stop, you are done. If this does not work, the carburetor might be damaged. You can either rebuild the carburetor or replace it.

Blocked Air Filter

Your hedge trimmer has an air filter to keep foliage, leaves, clippings, debris and dust out of its system. Unfortunately the filter will eventually accumulate so much debris that it prevents air from reaching the engine. If you clean the air filter regularly, your chainsaw will work better. The Wen 16 inch chainsaw is good as it is, but with a clean air filter it runs even better.

Gas hedge trimmers need air in the fuel to run. Without air the trimmer will not be able to continue running. A dirty air filter also increases the temperature inside the engine, which can cause overheating.

Solution. Clean the air filter.

There are two types of air filters, paper and foam. Paper air filters are not reusable so once it gets dirty you have to replace it. Most hedge trimmers use a foam filter or something similar so it can be cleaned and reused.

How to clean a hedge trimmer air filter

  1. Turn the hedge trimmer off.
  2. Find the air filter cover. This information will be in the manual.
  3. Remove the filer cover. You will see the filter. Remove it carefully. Wipe any dirt on the housing.
  4. Wipe dirt from the air filter. A wire brush will do. For caked dirt, wash the filter under running water. You can wash it with soap if necessary. Once the air filter has dried, put it back in place. Put the cover on and try the hedge trimmer again. If the air filter has a tear, replace it right away. Look in the manufacturer site for a compatible air filter.

Clogged Spark Arrestor

A spark arrestor is a device used to prevent sparks and possible fire from the engine. It prevents any combustible or flammable material from coming out of the hedge trimmer.

If the arrestor is dirty, the risk of sparks goes up. In addition, a clogged spark arrestor blocks exhaust from getting out of the trimmer. This can cause your hedge trimmer to start and stop.

Solution. Clean or replace the spark arrestor.

First thing you have to do is find it. The location of the spark arrestor varies, but is it usually somewhere close to where air departs the motor. Your owner’s manual has information about this so use that as reference.

When you find the spark arrestor, check for signs of damage. If there is you have to get a new one. Cleaning will not help and only a new one will suffice. If the arrestor is dirty but not broken, clean it with a wire brush.

Dirty or Damaged Fuel Filter

The fuel filter is responsible for keeping the fuel pure and clean. The filter keeps debris and dirt away from the carburetor to avoid contaminating the fuel mixture.

But fuel filters can only hold out dirt for so long. At some point the dirt will build up and clog the filter. This causes several problems. It prevents air from reaching the fuel, altering the mixture. Under certain conditions, this can cause the engine to falter.

Another problem is the dirt buildup increases the heat level in the motor. An overheating motor is never a good thing and can cause the hedge trimmer to stop running.

Solution. Replace the fuel filter

The fuel filter is in the fuel tank and linked to the fuel line. Remove the fuel filter and you should be able to see if it is clogged. If so, replace it with a new one.

Old Fuel in the Tank

All gas powered hedge trimmers will need fresh fuel every 30 days. If you have no plans to use the hedge trimmer for a while, remove the fuel or put stabilizer in the tank. This is necessary to prevent the fuel from turning into a gooey residue.

Almost all hedge trimmers are 2-stroke so you have to mix the gas and oil. The ratio will be either 40:1 or 50:1. If the fuel is old it will no longer have the same quality as before, more so if you are not using the trimmer.

Solution. Add new oil.

Turn the trimmer off. Drain the oil. Clean the tank and the rest of engine. Wipe off all the residue left. Add the gas and oil. Turn on the trimmer and let it idle. Use only the gas and oil recommended by the manufacturer. Do not alter the mix ratio because it could adversely affect how the hedge trimmer works.

Clogged Spark Plug

The spark plug is responsible for the spark that ignites the fuel. If the spark plug is damaged or covered with oil residue, the engine cannot receive the maximum amount of fuel available. The hedge trimmer may not start or it could stall while idling.

Solution. Clean or replace the spark plug

Remove the wire hooked up to the spark plug. Carefully pull the plug out. Check carefully for any signs of damage. Spark plugs are cheap so you can easily find one. Just make sure that what you get has the exact specs as the current one.

If the spark plug is not damaged but covered with carbon deposit, clean it with a wire brush. Put the spark plug back in and try the hedge trimmer again. If the engine tends to run hot, you can install a cooler running plug.

Low Battery Power

If you are using a cordless hedge trimmer and it won’t stay running, it is probably due to low battery power. There is enough to start the trimmer but as you start cutting, its power drains quickly.

Solution. Recharge the battery.

This is a simple plug and play. Plug the battery and wait for it to fully charge. This might take a few minutes to more than hour depending on the trimmer and how drained it is.

If the battery is fully charged but loses power quickly, the battery itself might need replacement. You can find one from the manufacturer website.