Hedge Trimmer No Spark (Solved)

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Hedge trimmers that do not have a spark will not run, period. This can be frustrating especially if you have a lot of work to do. There are many reasons why this can happen, and usually the problem can be solved without going to a technician. In this post we have compiled a troubleshooting guide that walks you through the solutions step by step.

A dirty or damaged spark plug will not produce any spark and stop the hedge trimmer from working. Clean or replace the spark plug and try again. Two other reasons why this happens are loose wiring and a faulty ignition module.

Safety First

  • Before anything else, observe these safety guidelines.
  • Wear gloves and safety goggles. Whenever you use, clean or repair a hedge trimmer, always war protection for your eyes and hands.
  • Unplug the hedge trimmer from the power outlet if it is an electric model. It is not sufficient to simply power it off because you might turn it on by accident. If you have the Husqvarna 21.7cc or other gas trimmers, no unplugging is needed.
  • Do the repair in a well-lit, ventilated environment. It is best to do this in your garage or shed. Stay away from any combustible objects.
  • Be careful when handling the spark plug and other parts.
  • When removing screws and bolts, set them aside in a safe location. You will need those to put everything back together.
  • If your hedge trimmer is too hot, turn it off and wait for the engine to cool before attempting any repair.

Faulty Spark Plug

The spark plug creates the spark that ignites the fuel in the engine. Without the spark your hedge trimmer will not run. If there is no spark in the machine, this is the first place you should look. A spark plug tester such as the Ram Pro will let you know if the plug is still working or not.

How to fix it

Turn the trimmer off and remove the spark plug. Check for signs of erosion, wear, breakage or any other damage. Replace the spark plug if it is damaged. It is good practice to replace the spark plug once a year for optimum performance.

The replacement must have the exact specifications as the one on the trimmer. If the spark plug is not damaged and just dirty cleaning will be enough. Through constant use, the spark plug will end up with oil and other dirt. A typical spark plug is gray or brown. If it has turned black due to oil or dirt, clean or replace it.

Reinstall the spark plug after it is cleaned. Turn the hedge trimmer on. If it runs you are done. If it does not, cleaning is not enough and you have to replace the spark plug. If the plug is more than a year old, it should be replaced even if there are no signs of damage.

Loose Wire

Loose wiring can lead to a loss of spark and prevent your tool from starting. Checking up on the wire is one of the first things you should do when repairing an electric hedge trimmer.

How to fix it

Loose wires can happen more often than you realize. If you are trimming hedges outdoors and walk too far from the power outlet, the cord might come loose. Suddenly the trimmer has no power and when you start it there is no spark. There could also be loose wiring on the hedge trimmer itself. Check the spark plug if it is connected.

If you are using a corded hedge trimmer, the cord length must be sufficient. A better option is to use a cordless hedge trimmer. Change it to full power, unplug the cord and start trimming. Reconnecting the wire usually works fine. But if it is worn out you have to replace it right away. Never use old, damaged wires on any hedge trimmer.

Test the Ignition Module

Also known as the ignition coil, it generates the current that enables the spark plug to ignite the fuel. Because it plays a huge role, any problem with the coil can cause your hedge trimmer to stop working. If there is no spark, this is one area you have to check.

How to fix it

What you need to do is test the ignition coil.

  1. Remove the nine cover and look for the coil. The location may differ from one trimmer to another. Check your manual for the exact location.
  2. When you find the ignition coil, look for the spark plug war that leads to the module. You will eventually find two small wires.
  3. Get an ohmmeter. First you have to test the switch. Turn it off and on. If the ohmmeter changes the switch is working. If it does not, the switch is broken and should be replaced.
  4. Now you have to test the spark plug. There are two ways to do this. First is with a spark plug tester. The second is to remove the spark plug and ground it at the engine block. Next, pull the starter rope. There should be a spark.

If there is none, you have to replace the ignition module. The new module must be exactly the same as this one or the trimmer will not run. Once you have the replacement, install it and reconnect all the wires.

Check the Switches

All hedge trimmers have a switch that can stop power from reaching the engine. It does so by stopping power from moving into the ignition coil. If this is not working properly it will affect the way your hedge trimmer operates.

How to fix it

Turn off the trimmer and lift the engine cover off. You might have to remove some screws for this. Look for the ignition coil. The location varies so check your owner’s manual.

Get an ohmmeter and look for two small wires on the ignition coil. Turn it off and on. If the ohmmeter changes when you turn the wires on and off, the switch is working. It is not the cause of the problem. But if the ohmmeter does not change, then the switch is damaged and must be replaced.

This switch cannot be fixed. Tinkering with it could make things worse and void the warranty if it is still applicable. Manufacturers have replacement switches available so you can buy one. When you have the switch, install it and try the trimmer again.

Check the Carburetor

Without the carburetor there is no way for a 2-stroke engine to combust. So if there is a problem with the carburetor the engine will not function. Follow these steps to diagnose problems with the carburetor.

How to fix it

Find the carburetor. It will be udder the air filter so remove that first. While you are at it, clean the air filter too.

  1. Remove the screws and bolts on the carburetor. Take off the throttle cable.
  2. Lift the carburetor off. Use a brush to clean the carburetor. If it is rally dirty, use a cleaning solution for carburetors.
  3. Take note that if there is corrosion you will have to replace the carburetor. If there is none, cleaning will be enough.
  4. After you have replaced or cleaned the carburetor, put everything back together. Turn the hedge trimmer on. Assuming the spark plug and other parts are working, the trimmer should start.

Clogged Fuel Filter

The fuel filter screen out dirt so the air and fuel can ignite in the combustion chamber. However the fuel filter will get dirty through heavy use. When this happens, the filter will no longer be able to prevent dirt from polluting the system.

How to fix it

Fuel filters take a long time to get clogged. Depending on how often you use the hedge trimmer it might take several months or years to replace one. When a fuel filter gets covered with oil or dirt, the best solution is to replace it. You should only buy a fuel filter that is 100% compatible with your hedge trimmer.

The fuel filter is not always connected to spark issues. But it is worth checking out since it affects the combustion. While examining this filter, you might also want to look at the fuel line for signs or breakage or damage.