How to Start a Chainsaw that Won’t Start (7 Reasons Why Your Chainsaw Won’t Start)

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Most of chainsaw users often face a common issue while starting their chainsaw.

Their chainsaw won’t start has spark and fuel though. Has your chainsaw dragged you into this situation as well? 

If you are also facing this type of problem. If so, don’t worry.

In this chainsaw guide, We pinpoint most of the common starting issues and their solutions. There are several possible issues behind such a situation no matter how much effort you’re giving.

You’ll learn how to start a chainsaw that won’t start, and how to fix it. You’ll also learn my top tips to prevent this from happening ever again.

So, Let’s get started!

1. Check on a Fuel

Gas gets overlooked a lot. We still assume there’s a major problem with the oily parts of our kit when very often the problem is pretty easy to fix.

Gas goes stale, and you may be surprised to know that it can go off in as little as one month. It loses its Oomph, the symptoms include, no starts, lacks of power bogging down, stalling, surging, and everything between.

Lots of gas today is a blend of ethanol, this type of fuel attracts moisture, and that invites trouble.

When a customer shows up in my workshop complaining of  a lazy starting saw after sitting, I’ll always suspect bad gas.

I have a pretty good nose for bad gas. If you suspect that your gas is older than one month, then go ahead and empty the gas tank and fill it with a fresh mix of gas and two-stroke. For many saws, this is enough to get the saw recommissioned.

Gas Shot

If after refilling with fresh gas the saw still won’t start, I’ll try a gas shot directly into the carburetor. Because sometimes bad gas needs a little help to flush from the carburetor.

The results of the gas shot will have three possible outcomes.

Go ahead and try the gas shot,  remove your air filter (most saws won’t require any tools). Take a cap full (thimble size) of fresh gas and drop it into the carburetor.

Go ahead and try to start the saw in the normal way.

Outcome 1: Saw starts and stays running, you got lucky and your work is done sir.

Outcome 2: Saw runs and stalls. Repeat the process 2-3 times and if it continues to stall, you’ll need to remove and clean the carburetor (see clogged carburetor).

Outcome 3: Saw makes absolutely no attempt to start. You may have an ignition system fault (see plug fault)

Read MoreBest 18 Inch Electric Chainsaw

2. Take a Look at the Carburetor

Unfortunately, we’re going to need to perform surgery on this patient. The stale gas has likely congealed inside the carburetor and blocked up tiny fuel passageways. It’s not uncommon to remove the carburetor and find it’s too badly clogged to repair.

Carburetor manufacturers offer carb kits that include gaskets, gas needle valves, and arms. It’s good practice to replace these as your going to dismantle the carburetor anyway, but it is possible to reuse the same parts.

As an alternative just go ahead and replace the complete carburetor as you’ll find in most cases replacement carburetors aren’t expensive. New carbs come with a guarantee, tested, tuned, and ready to fire out of the box.

If I have any doubts about the carb I’m working on, I’ll bounce for a new one.

Tools You’ll Need

Removing the carburetor on some chainsaws is a pain in the ass, but for most, you’ll find it straight forward.

But working on saws isn’t like working on your car, truck, or even mower. The parts are tiny and real-estate tight, You’ll need bags of patience and if you’ve got Shrek hands, you might want to take a pass on this repair.

Special carburetor adjuster tools will be needed for some saws, but other than that just a selection of sockets, screwdrivers, carb cleaner, carb cleaning tools, and my special top tip – gas stabilizer additive to stop this from ever happening again.

Replacement Carburetors

If you’ve decided to replace your carburettor, be sure to order the correct model.

Your carburetor is calibrated to the power output of your saw. So, although a family of carburetors looks identical, they are different.

You’ll find most saw manufacturers don’t actually make their own carburetors. They use the third party well known and trusted carburetor manufacturers, like Walbro and Zama.

So when you have removed your carburetor check the make and model stamped into the body of the carburetor. Then check out this page “Small engine carburetors”, I’ve listed all the most common types where you can check price and availability on Amazon.

After cleaning or fitting a new carburetor, be sure to clean your gas tank and fit a new gas filter.

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3. Spark Plugs Might not be Sparking

Plugs have a tough job, and they live in a hostile environment. They’re right there in the thick of all the action. Wedged in a hot cylinder next to a hot muffler, it’s no wonder they are number three on the list of possible causes. You’ll find plugs are pretty tough components, they can work tirelessly for years without ever missing a beat.

A plug should be changed at the start of each new season, but I live in the real world and most owners won’t give the plug a second thought, so long as it’s doing its job.

If you are treating your saw to a new plug, be sure to get the right one, plugs come in different thread thicknesses, lengths, and heat ranges.

Check your make and model for the correct spark plug part number.

Checking Spark

A spark plug test tool is the best way to check the ignition system. The tool stresses the ignition system and if it’s faulty it will show up. Don’t have a spark test tool? Not to worry, we have a hack.

Checking spark without a test tool, go ahead and:

  • Remove the spark plug
  • Ground the plug body against the saw metal body (I use a jump leads to help get a good connection)
  • Set the switch to “On” and pull start the saw
  • Observe the spark plug for spark

If you’ve got spark, great! All is good here.

No Spark From Plug

No spark at the plug doesn’t necessarily mean you have a major problem.

Check your plug, there should be a visible gap between the tip and the electrode. If the gap is closed, open it using pliers or a flat screwdriver.

The plug should be free from oil and carbon, if not clean the plug using a wire brush. Now test again for spark.

Or if you have a spare plug or a known good donor test plug, swap it. Now crank over the engine and check for spark again. Still no spark, you’ll need to check the armature (See below).

4. See if the Engine is Flooded

how to start a chainsaw that won't start

So what is flooding? It’s basically too much gas in the combustion chamber, of the engine. Instead of the spark plug igniting the gas, the excess gas simply extinguishes the spark. No spark equals no fun!

So why does it happen? Flooding often happens when the engine is repeatedly cranked over without the engine actually starting. It very often occurs as a result of another underlying problem, such as bad gas, bad spark plug, overuse of choke, or just a faulty carburetor.

A saw that isn’t well maintained is prone to flooding.

So how can you fix it? There is three ways to fix a flooded chainsaw:

  1. Just let the saw sit for 30 min and the excess gas will evaporate.
  2. Remove the spark plug, dry it, crank over the engine a few times to dry the cylinder. Now refit the plug and try again.
  3. Set the switch to “On”, set throttle to fully open, set choke to “Off” and crank over the engine. Expect the saw to start on the second or 3rd pull.

How can you prevent flooding? Make sure your gas is fresh and your saw is tuned-up.

5. Inspect The Air Filters

The air filters are there to protect any debris from getting into the engine. The air filter, however, is also where the air will come from in order to be mixed with the fuel. If this is blocked, then the engine is going to struggle to get the oxygen it needs.

All filters will get clogged or dirty over time as that’s their job. Due to this, regular maintenance is required to clean them out. If your filter has been in there for a long time or is very dirty then it’s probably going to be a good idea to buy a new one.


6. Check the coil and springs

What we have looked at already covers the vast majority of times when a chainsaw won’t start. If you’re still left scratching your head then you need to delve deeper into the system and the problem might be with the ignition coil or rewind spring.

The ignition coil sends the electricity through to the sparkplug and without this, they simply won’t spark. They have testers for ignition coils available but you can also use a multimeter. If that’s the root of the issue then you simply need to replace them and your chainsaw will be working once again.

The rewind spring can also be a problem as this is what’s meant to allow you to repeatedly pull the starter cord. Unfortunately, this can end up being a very big issue as unless you can replace the spring, the recoil starter assembly might have to be completely removed.

The recoil starter assembly might also be a part of a bigger problem. One way to test it is to remove the assembly and pull the cord, to make sure the tabs are working correctly. If they aren’t then your only solution is going to be completely replacing the assembly.

7. Check The Armature

A faulty armature (aka a coil) is a pretty common failure. The armature with the flywheel creates the high voltage the spark plug needs to fire.

Armatures commonly fail in one of two ways. They will often work OK when the machine is cold and then stop working as the machine heats up. Or, they’ll just stop working period.

Testing The Armature

Testing the armature starts with the spark plug test we did earlier, ideally we would use a proper tool to test the ignition system. The test tool loads up the armature and will reveal any weakness, our hack with the plug isn’t foolproof.

You can check out the test tool on this page along with some other useful kit “small engine repair tools”.

Testing is simple, go ahead and:

  • Remove pull assembly cover (4 screws usually)
  • Remove coil control ground wire
  • Refit pull assembly
  • Check spark as before

Still no spark? go ahead and replace the armature.

Or if you now have spark, check for shorting on the on/off switch wiring (damaged wiring).

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