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6 Reasons a Chainsaw Won’t Start When Hot (FIXED)

You shut off your chainsaw momentarily or it ended up dying on you. Now you can’t get it started again. I’ve provided the most likely reasons for this condition below.

A chainsaw won’t start when hot due to a flooded engine, wrong choke setting, dirty carburetor, dirty spark plug, faulty ignition coil, plugged fuel tank vent, or vapor lock.

Follow the safety precautions provided in your chainsaw operator’s manual. Always remove the spark plug wire before making any repairs.

Chsainsaw spark plug

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Fix Your Chainsaw Starting Problem: Won’t Start When Hot

1. Engine Flooded / Incorrect Starting Procedure

The choke is required to restrict airflow when starting a cold engine. This is because a cold engine requires a rich fuel mixture allowing more fuel and less air to start.

Once the engine warms, the choke lever or knob must be placed in the off position so the engine gets enough air to keep running. Failing to make this choke adjustment can cause the engine to die.

A cold engine won’t start without the choke engaged and a warm engine won’t start with the choke engaged.

When the choke is closed and the starter rope is pulled too many times the engine can become flooded and won’t start.

It can also happen with the switch off and the starter rope being pulled multiple times or when the primer bulb is pushed too many times.

This isn’t a serious problem and can be easily fixed using one of the options below.

SOLUTION: When starting an engine that is already hot, don’t engage the choke. Doing so will flood the engine allowing too much gas into the cylinder.

How to Fix a Flooded Engine on a Chainsaw – Option 1

  • Place the on/off switch in the on position.
  • Place the choke knob or lever in the open/run position.
  • Press the throttle lockout and squeeze the trigger while pulling the starter rope over and over. This can take anywhere between 5 and 15 pulls before it starts. Your chainsaw engine will sputter first. Continue to pull 2 to 3 more times and it should start.

How to Fix a Flooded Engine on a Chainsaw – Option 2

  • Place the switch in the stop/off position.
  • Remove the spark plug and clean it
  • Pull the starter rope 6 to 8 times.
  • Reinstall the clean dry spark plug.
  • Turn the switch to the start/on position.
  • Start the chainsaw with the choke off and in the open/run position.

2. Dirty Carburetor

The carburetor regulates the amount of gas that is mixed with the air required for your chainsaw to start and continue to run.

The passageways can become clogged and the small components can fail to function correctly which can be the reason the chainsaw stops running.

Old fuel is a big reason why a carburetor will stop working.

SOLUTION: You may be able to clean or rebuild your carburetor to get it working again. You will have to replace the carburetor if this doesn’t work.

3. Bad Spark Plug

A dirty or broken spark plug won’t provide the consistent spark needed to start and run a chainsaw. It may provide intermittent spark causing the saw to no longer start when hot.

Inspect the condition of the spark plug tip. The spark plug must be replaced if it is very dark in color and has a broken porcelain or burnt electrode.

You can try to clean the spark plug with a wire brush and reuse it if it’s just a little dirty. I prefer to just replace it. It’s an important part required for your chainsaw to start and run well. It’s also an inexpensive maintenance part.

Make sure the spark plug is gapped correctly and the spark plug wire is securely attached. (Don’t leave the spark plug attached if you need to continue to make additional repairs).

4. Faulty Ignition Coil

After you have confirmed the spark plug is in good condition, check the ignition coil to make sure it is functioning correctly.

The coil provides the electrical current to the spark plug to form a spark that ignites the fuel to start and keep your chainsaw running.

When the coil gets hot, the winding on the coil can separate and short out. This will cause your chainsaw to fail to start when there is intermittent or no spark.

A bad ignition coil will not be able to provide sufficient voltage to the spark plug.

SOLUTION: Test the ignition coil and replace it if you find there is a break in continuity.

5. Plugged Fuel Tank Vent

The fuel tank on a chainsaw must be able to vent to allow air to pass into the tank.

Air must be able to pass through the vent and out of the tank when fuel is added. Air also needs to be able to pass into the tank when the fuel level decreases.

When the tank isn’t able to vent, vacuum forms that will prevent fuel from leaving the fuel tank to flow to the carburetor. This will cause the chainsaw to die and not restart until the fuel tank is able to get air.

SOLUTION: Locate the fuel vent on your chainsaw and replace a clogged vent. It is a small circular part that is installed on the top side of the tank.

6. Vapor Lock

When the fuel mixture in a chainsaw heats up it may vaporize creating bubbles that interfere with fuel getting to the engine. The chainsaw may not start until it cools down.

SOLUTION: Allow the chainsaw to cool. To reduce vapor lock conditions, always use fresh fuel and air-cooled engine oil.

You are more likely to experience vapor lock when running the saw in very hot conditions and for extended periods.

Take caution removing the fuel cap. When the fuel tank is under pressure, fuel can spray out of the fuel tank when removing the cap.

Still Having Troubles With Your Chainsaw?

As a chainsaw owner, you’re going to run into problems with it occasionally. This is true of all chainsaws.

To help you quickly identify the cause of your problem and how to fix it, I’ve put together a handy reference guide.

You will find charts with problems and solutions to many common issues along with links to information in more detail.

Check out Common Chainsaw Problems for help solving problems with your equipment not starting, the chain not turning, the engine dying, a loss of power, and more.