Top 13 Causes of a Failed Chainsaw Start

When there is a lack of air, gasoline, and spark, a chainsaw will repeatedly start and shut down.

This may be the result of a blocked air filter, dirty carburetor, blocked fuel filter, improper choke adjustment, a clogged fuel tank vent, a blocked spark arrestor, a broken ignition coil, or a blocked cooling system.

For other explanations as to why a chainsaw could stop working, please read on. Remove the spark plug wire from the chainsaw before making any adjustments. Don’t touch anything until the engine and muffler have cooled down and all moving parts have stopped.

Why Your Chainsaw Sparks but Never Fires

Incorrect Choke Position on a Chainsaw

In order to get a cold engine going, you need to utilize the choke to limit airflow and make the fuel-air mixture richer. To start the engine, this allows for a leaner mixture of fuel to air.

Choke off once engine is heated to adjust fuel-to-air ratio and prevent engine from running rich.

A sluggish or dead engine is usually a result of the choke not being in the off/open position.

The Problem with a Chainsaw’s Clogged Air Filter

The air filter on a chainsaw is a component used for upkeep that prevents debris from entering the carburetor throat and wearing out the engine. It is imperative that this filter be maintained regularly.

The typical homeowner should check the air filter several times a year and clean or replace it as needed.

Filters can become clogged with dust, sawdust, and other material if routine maintenance is neglected. When the accumulation is bad enough, it might restrict airflow through the filter. If this occurs, the chainsaw will become inoperable.

A Chainsaw With Its Cooling System Clogged

A dirty cooling system will cause the engine to overheat, shut down, and waste fuel. Cleaning the engine’s air intake and cooling fins of dirt and debris will assist keep the engine running cool.

To accomplish this, turn off the engine and wait for the spark plug to cool down. Clean the outside of the cylinder and the engine cover by removing them.

The chainsaw’s airflow can be improved by cleaning the pawls on the flywheel, the cylinder cooling fins, and any other openings. Put the engine cover back on. Keep the chainsaw’s exterior, including the starter’s air intake, clean.

Clogged Chainsaw Spark Arrestor

The muffler is equipped with a spark arrestor screen to prevent sparks from flying out of the exhaust system.

A buildup of carbon on this screen can prevent exhaust air from escaping the muffler, causing the muffler to stop working if it is not cleaned periodically.

Start by disconnecting the spark plug wire and letting the muffler cool down before cleaning the spark arrestor. Then take off the muffler’s spark arrestor screen.

Utilize a metal brush to thoroughly scrub the display. A new spark arrestor screen should be installed if the existing one is severely soiled, broken, or full of holes.

Be sure to run your chainsaw at full throttle on a regular basis to reduce the rate at which carbon accumulates on the spark arrestor. A buildup of carbon is facilitated by prolonged periods of idling or low-speed operation of the chainsaw.

Using Outdated Gasoline in a Chainsaw

A lack of fuel is a common cause of chainsaw breakdown and failure. The varnish and sticky deposits left behind by old fuel might block fuel components, reducing the amount of fuel reaching the engine. Because of this, the saw may suddenly turn off.

It is recommended that you use gas with no more than 10% ethanol in it to prevent damage to your chainsaw.

How to choose and maintain fuel, including some helpful hints:

• If you’re going to burn something, make sure it’s new fuel. As little as 30 days after purchase, fuel quality might start to decline.
• Put in quality fuel. The fuel needs of 2-cycle and 4-cycle chainsaws are distinct. It can be killed by using the incorrect gasoline.
  2-cycle motors: the standard gas/oil ratio for a chainsaw is 50:1. It’s possible that you’ll find that a 40:1 ratio is necessary for others. Here you may learn more about chainsaw fuel.
• Choose fuel with an octane value of 89 or higher and no more than 10% ethanol.
• Add in some high-quality 2-cycle oil that has been approved by ISO-L-EGD and JASO M345 FD.
• For a 4-cycle engine, never combine oil and gasoline. Both gasoline and diesel can be fueled through their own dedicated ports.
• Choose gas with an octane value of 89 or above and no more than 10% ethanol.
• The gasoline must be stabilized. Add a fuel stabilizer, such as Sea Foam or STA-BIL, to your gas tank to keep it from degrading prematurely. In addition to drying out the fuel system, these solutions will also clean it.

Chainsaw With A Clogged Fuel Filter

To prevent harmful debris from entering the fuel system and damaging the engine, a fuel filter is installed. Inside the fuel tank is a little cylinder-shaped component called the fuel filter.

The fuel filter is connected to the fuel line. If you don’t change your filter regularly, dirt will build up and prevent enough gas from reaching your engine’s carburetor.

Take a look at the filter and swap it out if it’s worn. One yearly swap, or more frequent swaps if I start using it frequently.

During the winter, I use my saw frequently; in other seasons, not so much. In my experience, fuel filters should be changed twice a year, just before and during the coldest months of winter.

How to Replace a Fuel Filter on a Chainsaw

• The fuel tank cap should be wiped down first to prevent any dirt from entering the tank.
  
• You can use a filter hook or a clean, bent wire to remove the filter from the tank.
  
• When you’ve removed the filter from the tank, you can grab the fuel line with one hand and the filter with the other.
  
• Replace the existing gasoline filter with a new one.
  
• The fuel filter should be installed within the tank.
  
• Put the gas cap back on.7. Clogged or Punctured Fuel Line on a Chainsaw

Old fuel’s gummy residues might plug the fuel line, preventing fuel from flowing. If the chainsaw’s fuel line becomes blocked, you can remove it and clean it.

Clean the line with carburetor cleaning and try to remove the obstruction. To eliminate the obstruction, follow up with a blast of compressed air. Simply keep trying until the obstruction is gone.

The gasoline line must be replaced with a new line of the same diameter and length if the blockage cannot be removed or if the fuel line is dry and broken.

If there is a hole in a line, please replace it. If the gasoline line on a chainsaw is damaged, air can enter the fuel system and cause the cylinder to operate poorly.

Unable to Run Chainsaw Due to Blocked Fuel Tank Vent

The fuel tank of a chainsaw needs to have a vent so that air may enter it when fuel is used. A vacuum will create in the absence of a vent, blocking the fuel supply from reaching the carburetor.

Find the chainsaw’s fuel vent and clean or replace it if it’s clogged. It is a little circular piece attached to the top of the gasoline tank on most chainsaws.

Chainsaw with a Filthy Carburetor

Your chainsaw won’t fire up without the carburetor properly blending air and fuel. It’s possible for the chainsaw to stop working due to clogged passages or malfunctioning tiny components.

The major cause of a carburetor failing is usually stale fuel. Your carburetor may be fixable by cleaning or rebuilding. If it does not work, you will need to get a new carburetor.

The Chainsaw’s Carburetor Requires Fine-Tuning

Changing the RPMs at idle and full throttle may require adjusting the carburetor. The carburetor features a set of adjustment screws for just such purposes.

We provide both slow and fast screws. Let the chainsaw idle, and then turn the low-speed screw clockwise and counterclockwise until the chainsaw is running smoothly and quickly.

Then, you should tweak the high-speed screw until the engine has a nice, consistent RPM when you’re giving it the whammy. You could do serious damage to the engine if you allow the RPMs to become too high.

There are often strict limits on what kind of carburetor changes you may make on a chainsaw from the manufacturer.

You should take your chainsaw to a professional if you are having issues with the carburetor or if your saw does not have a mechanism for adjusting the carburetor.

Your dealer may be the only one who can make the necessary modifications because they require a unique tool.

A Chainsaw with a Faulty Spark Plug

A chainsaw won’t be able to run if the spark plug is unclean or damaged since it won’t produce a constant spark. A lack of consistent spark could render the saw inoperable.

Check the spark plug for damage at the tip. To replace a spark plug, check for a very black color, shattered porcelain, or a scorched electrode.

If the spark plug is only slightly soiled, you can attempt cleaning it with a wire brush before throwing it away. In most cases, I find it easier to just buy a new one. It’s important to keep this component in good working order to ensure the smooth operation of your chainsaw.

Ascertain that the spark plug wire is firmly attached and that the space between the electrodes is appropriate. (Remove the spark plug before proceeding with further maintenance).

Failure of a Chainsaw’s Ignition Coil

Assuming the spark plug is in good shape, the ignition coil is the next component to inspect. In order to start and maintain operation of your chainsaw, electricity must flow from the coil to the spark plug.

The coil’s winding can come unwound and cause a short when it becomes too hot. Because of this, whenever there is an intermittent spark, your chainsaw will lose power, operate slowly, or stop running altogether.

If the ignition coil is malfunctioning, the spark plug will not receive an adequate voltage to ignite.

Engine Compression Issues with a Chainsaw

There could be a drop in compression as you draw the starter recoil rope. Reduced pressure from insufficient compression renders a chainsaw useless.

The crankshaft seals, piston rings, or piston itself could all be to blame for this issue.

I suggest having a small engine technician or a chainsaw dealer inspect, service, and fix your chainsaw.