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Why Won’t My Chainsaw Start? 6 Things You Should Check

Chainsaws are complex machines, and figuring out ‘why won’t my chainsaw start‘ can be a long, drawn-out procedure.

Even worse, figuring out why your chainsaw won’t start is made even harder by the fact that even the smallest thing can cause your once perfectly fine chainsaw to transform into nothing more than a large paperweight.

With that in mind, in today’s guide, we’re going to list some of the many reasons your chainsaw won’t suddenly start, as well as some possible solutions you can employ to get it back on track.

Why Wont My Chainsaw Start
Seeking advice. I can’t get this chain on. – via Reddit

Why Won’t My Chainsaw Start?

A myriad of factors could’ve stopped your chainsaw from running, including complex issues like engine compression problems, damaged carburetor, dirty air filter, or even a bad spark plug. Some of the simpler problems include wrongly calibrated high-low adjustment screw, bad fuel, or a broken fuel line.

Whatever the reason, this guide below should help you figure it out.

Bad, Clogged, Dirty Carburetor

If you’d like to dive off into the deep end, start by checking your chainsaw’s carburetor. Clogged carburetors will usually cause a chainsaw’s engine to either not start at all or to stall.

If you find that the carburetor has been clogged, you could try cleaning it using a carburetor cleaner. If that fails, take it out for a deeper cleaning session. You could even employ automotive carburetor cleaners to do the job.

If you have the patience and time, you could also invest in a carburetor rebuilding kit. These kits retail with all the components that tend to get damaged or worn out on chainsaws, as well as sets of fresh O-rings and gaskets. Once you’ve rebuilt and cleaned your carburetor, it is time to put it back nicely and test if your fix efforts were worthwhile.

If the chainsaw works, hurray!

If it doesn’t, then your carburetor may be damaged beyond repairs, and you’ll need to replace it. Once you ascertain that the carburetor is the issue, you could also prefer to just invest in a new chainsaw altogether. Of course, it’ll cost you more compared to replacing the carburetor, buts its’ also much easier and faster.

With that in mind, if you opt to replace the carburetor, remember to also invest in new gaskets you can place between the manifold and the carburetor. Also, replace the gas and fuel filter to give your machine a fresh, clean start.

Compression Issues

Prior to your chainsaw not starting, did it not feel as powerful as it was when it was new, was it having a hard time starting, or did it show signs of lack of sufficient lubrication? If you answered yes to any of the scenarios above, you should probably do a compression test on your chainsaw.

A healthy chainsaw engine should have at least 100 PSI (if you’re dealing with a bigger engine saw) or more than 70 PSI for smaller saws.

Regarding how you can carry out a compression test, you can invest in a cheap compression tester gauge, which are readily available in the market. If you’re not comfortable doing it yourself, take your chainsaw to a specialized shop, and they’ll do the testing for you.

What’s more? If you learn that your chainsaw has low compression, it signals that there could be internal damage, like cracked pistons, bad crankshaft seals, or bad piston rings. Honestly, fixing damages like these is usually extremely expensive and is a sign that it’s probably time to invest in a new chainsaw.

Why Wont My Chainsaw Start 2
C/S: Chainsaw doesn’t run right – via Reddit

The Carburetor Needs Calibrating

As your chainsaw’s engine and components wear out, the carburetor we discussed earlier might need some adjustments. To do this, chainsaws retail with three adjustment screws that you can use to give the chainsaw engine proper airflow.

Note, though, that adjusting a carburetor in a chainsaw is no easy task. Different models have distinct settings, and some will prove impossible for untrained individuals.

Another point worth noting is that while you’re turning the screws in your chainsaw engine to give it better airflow is that you will also be adjusting the air-fuel ratio of the engine. If you accidentally leave the fuel mixture too rich or too lean, it can be quite harmful to your chainsaw’s engine.

That’s why I always advise my readers to take their chainsaws in need of calibrating to a service shop if they’re not sufficiently trained to handle such issues.

Broken or Clogged Primer Bulb

Some chainsaw models retail with a primer bulb. Does your chainsaw have one? If it does, this primer bulb could be struck with oil and/or fuel. Its material can also crack due to exposure to the elements. These cracks, in turn, allow air to escape, preventing proper idles.

If you learn this is the case, your chainsaw’s primer bulb needs to be replaced.

Bad Spark Plug

Bad spark plugs can not only prevent your chainsaw from starting, but they can also cause the chainsaw’s engine to lose power and stop. This power loss might not be apparent while your chainsaw engine is idling or working on softwood.

However, this might be the issue if your chainsaw engine stops while you’re cutting harder wood and won’t start up again. To fix it, I suggest removing the spark plug and inspecting it for signals of damage.

The things to look for include excessive light or damage in the electrode, carbon buildup at the electrode, and even cracks on the porcelain insulator.

Damaged or Blocked Idle Port

The idle screw, also known as the idle port, is included to adjust the airflow ratio into the chainsaw’s engine. Debris, dirt, and oil can all block them, preventing air from flowing into the engine. With that in mind, if your chainsaw’s idle port is damaged or blocked, your chainsaw won’t start.

Check the port for blockage or damage, and if you notice any, clean it using kerosene, alcohol, or any other solvent. If it’s completely damaged, you have no choice but to replace it.

Final Thoughts

Chainsaws are great tools invented to make our lives easier. As such, it’s always a horrible moment when they decide to breakdown out of the blue and when we need them the most. Thankfully, if you’re willing to put the time and effort into it and think out of the box, you may not have to give your saw up.