Chain Saw: Won't Start

The carburetor is one of the first parts you should check for clogging or damage if your chainsaw will not start. The carburetor is designed to mix fuel and air in the proper mixture for combustion. Over time, and especially if you’ve left fuel sitting in the carb, it can become clogged, and this will eventually starve the engine of fuel. When the engine doesn’t get enough fuel, or it doesn’t have the correct mixture of fuel and air, it may not start. Carburetors can often be cleaned and rebuilt with a new carburetor kit, to solve this issue. However, if the carburetor is too badly clogged, or you cannot get it clean, you may need to replace it.

A clogged air filter can cause your chainsaw not to start. If the filter is clogged, the engine won’t have the air necessary for combustion. Because the air filter is designed to prevent debris from entering the engine, it often becomes clogged with the very dirt and grime it is protecting the engine from. As part of your normal chainsaw maintenance routine, you should clean the air filter to prevent too much buildup. On most chainsaws, you can simply pop open the air filter cover, then remove the air filter. Clean or replace it with a new one, and often your chainsaw will start properly again.

Your chainsaw’s fuel filter prevents debris from entering the fuel lines and traveling up into the carburetor. Debris can cause clogs in the fuel lines as well as the filter itself, and this can make the engine impossible to start. Often it is possible to clean your fuel filter, and this will usually solve the problem. However, if your fuel filter is damaged, you may need to replace it. Replacing the fuel filter is usually as simple as disconnecting it from the fuel line and replacing it with the new filter. It is a good idea to inspect your fuel lines at the same time as the fuel filter, in case debris needs to be cleaned out of the lines as well.

The spark plug in your chainsaw ignites a specific mixture of air and fuel, which powers the engine. If the spark plug is damaged or dirty, or even improperly gapped, it will not fire properly, and this will prevent the chainsaw from starting up. Your first step toward checking your spark plug would be to remove it from the boot and check it for oily buildup. You may be able to clean the plug, re-gap it to the manufacturer’s specifications, and your problem will be solved. The plug might also be improperly gapped, which can cause the timing of the spark to be off, resulting in a chainsaw that won’t start. You can test your spark plug with a multi-meter to ensure it is still in working condition, but if it is not, it will need to be replaced before your chainsaw with start up properly.

The piston in your chainsaw create compression that is required for your chainsaw to start and run properly. The piston moves up and down to propel the engine, and if the piston or the cylinder is damaged, it can cause your chainsaw not to start. This is a significant issue, because the cylinder and the piston are some of the more difficult pieces to replace. Fortunately, the piston and the cylinder are less likely to be the cause of this issue than smaller pieces like the carburetor or the air filter. Occasionally, the piston’s O-ring will become damaged, and this will not allow compression to occur. If there is damage to the piston or the cylinder you will need to replace them before your chainsaw will start again.

Your chainsaw’s fuel lines carry fuel from the tank to the carburetor, and provide the engine with fuel for combustion. Broken or clogged fuel lines will prevent fuel from reaching the engine, making it impossible to start the chainsaw. Disconnect the fuel lines and inspect them for cracks. If you find a crack you will need to replace the line. If there are no cracks, try to blow in one end of the line to check for a clog. A clogged fuel line may be able to be cleaned, and the fuel line can be salvaged, but it is often wiser to replace the line, and prevent future clogs.

The ignition module, or ignition coil, creates a magnetic field with the flywheel, which induces electricity. Electricity then travels to the spark plug, and this allows it to ignite the fuel in the combustion process. A faulty or damaged ignition module can make your chainsaw difficult to start. However, if your spark plug will not produce a spark, it is likely a problem with the plug and not necessarily the fault of the ignition coil. If you’ve tested your spark plug, and it is in working condition, you should then test the ignition coil. You can do this by disconnecting the spark plug from the cylinder, and attempting to run the engine. If you do not see a spark from the spark plug after a couple of tries, it is a good indication that the ignition coil is damaged, and will need to be replaced. Be sure to read your safety manual when conduction this test and before completing the repair.