Chainsaw Won’t Start When Hot: 4 Easy Ways To Fix It Now

As a homeowner or woodworker, your chainsaw is a crucial tool in your arsenal – it makes quick work of cutting through branches and logs, allowing you to complete your projects efficiently.

However, it can be a real headache when your chainsaw refuses to start after a warm run. Suddenly, that once reliable tool becomes a source of frustration. But don’t let this common issue ruin your day; in many cases, the problem is easily fixable with a few simple steps.

In this article, we’ll dive into four reasons your chainsaw won’t start when hot, as well as four easy ways to get it up and running again, so you can get back to your projects with confidence. Whether it’s a clogged air filter, a worn spark plug, or something else, we’ve got you covered. So, grab your toolbox, and let’s get started!

Why Won’t Your Chainsaw Start When Hot?

Table of Contents

Let’s take a moment to review the four most common reasons chainsaws fail to operate when hot before we delve into solutions.

1. Vapor Lock

Have you ever been working with your chainsaw, and suddenly it just stops functioning, even though there’s still fuel in the tank? Chances are, you may be experiencing vapor lock. This occurs when excessive heat and vapor build up in the gas tank and cannot escape.

Vapor lock is especially common in chainsaws that have been exposed to the sun for an extended period of time. The increased heat causes vapors to accumulate in the fuel lines, causing the fuel to become less effective and sometimes even preventing it from flowing to the carburetor.

The chainsaw may start normally, but as you rev it up, the rising temperature only exacerbates the vapor pressure and restricts the fuel supply, causing the chainsaw to shut down.

2. Ignition Issues

Another common reason for a chainsaw to stop working is a worn or dirty spark plug. When the plug gets coated in black carbon, it can be difficult for the spark to ignite, especially when it’s hot. Other possible issues could be in the ignition module or the coil in the module.

If your chainsaw suddenly stops, try squirting a little starter fluid into the open choke valve located beneath the air filter. If it starts up, it’s likely a problem with the fuel system, but if it doesn’t, it could be an issue with the ignition module or coil.

This problem occurs when the spark plug electrode creates a spark to ignite the engine. It’s especially common in chainsaws that use Milwaukee batteries, so storing them properly is important to avoid this issue.

Check the electrode for any signs of wear or tear, as well as the unusual buildup of black carbon. Over time, this buildup can affect the quality of the spark, particularly at higher firing temperatures. If you find that your Homelite chainsaw is not starting, it may be because of this issue.

3. Plugged Carburetor

A third cause of a chainsaw dying out when hot could be an improperly adjusted carburetor. The carburetor regulates the amount of fuel and air mixture that is delivered to the engine. If the carburetor is set too rich or too lean, it can cause the engine to stall.

Over time, the fuel can leave behind white, sticky deposits that can clog the carburetor jets, blocking the fuel supply to the engine. This will cause the engine to overheat and eventually die out, as it’s not receiving enough fuel to generate the necessary power. This is a common problem with Husqvarna 562xp chainsaws.

4. Inadequate Compression

When it comes to operating a chainsaw, it’s crucial to compress the air-fuel mixture to the right temperature. This allows the mixture to generate enough power in the power stroke.

However, Poulan chainsaws can sometimes be a challenge to start when hot. This is due to the single-piston rings in the engine. Despite the proper functioning of the ignition system and fuel delivery, the piston rings may have worn down to the point where the compression drops to near zero at high temperatures.

Typically, the piston rings keep gases from escaping the crankcase and maintain pressure during the compression stroke. But with thermal expansion, the wear rate of the piston increases at high temperatures, leading to low compression.

How to Fix a Chainsaw that Won’t Start When Hot?

With the causes of hot chainsaw malfunction in mind, let’s move on to 4 solutions.

1. Vapor Lock Fix

Chainsaws that experience vapor lock – resulting in failure to start or stall when hot –  can be fixed with these steps:

  1. Check the fuel line: Inspect the fuel line for any cracks, kinks, or damage. If any damage is found, replace the fuel line to prevent the vapor lock from recurring.
  2. Clean the carburetor: Use a carburetor cleaner and a clean cloth to remove any dirt, debris, or buildup from the carburetor. This will help ensure that the carburetor is functioning properly and that the fuel and air mixture is mixed correctly.
  3. Check the fuel filter: Remove the fuel filter and inspect it for any signs of damage or clogging. If it is clogged, replace it to allow proper fuel flow to the engine.
  4. Allow adequate fuel flow: Ensure that the fuel line and fuel filter are not kinked or restricted in any way. This will allow for proper fuel flow to the engine, reducing the risk of vapor lock.

By taking these steps, you can resolve the vapor lock issue in your chainsaw and get it running smoothly again.

2. Ignition Issues Fix

A defective ignition can cause a chainsaw to not start or run poorly. Here are the steps to fix a defective ignition in a chainsaw:

  1. Check the spark plug: The first step in fixing a defective ignition is to check the spark plug. A spark plug that is worn, fouled, or damaged can cause the chainsaw to not start. Remove the spark plug and inspect it for any signs of damage or wear. Replace the spark plug if necessary.
  2. Check the spark plug gap: The gap between the spark plug electrodes must be set to the proper specification for the chainsaw to start and run correctly. If the gap is too large or too small, it can cause the engine to not start or run poorly.
  3. Check the spark arrestor: The spark arrestor is a small screen located in the muffler, preventing hot sparks from exiting the muffler and starting a fire. If the spark arrestor becomes clogged, it can cause the engine to not start or run poorly. Clean or replace the spark arrestor if necessary.
  4. Check the ignition coil: The ignition coil is responsible for producing the high-voltage spark required to start the engine. If the ignition coil is defective, it can cause the engine to not start or run poorly. Test the ignition coil and replace it if necessary.
  5. Run the chainsaw: After following these steps, it’s time to try starting the chainsaw. If it starts and runs smoothly, the issue of a defective ignition has been resolved.

With these steps, you can successfully repair a broken ignition in your chainsaw. Note that regular inspection and maintenance of the spark plug, spark arrestor, and ignition coil is crucial to prevent future ignition issues.

3. Plugged Carburetor Fix

A plugged carburetor can prevent a chainsaw from starting or cause it to stall. Here are the steps to fix a plugged carburetor in a chainsaw:

  1. Remove the air filter: The filter is located on top of the carburetor and can often become clogged with dirt and debris. To access the carburetor, remove the air filter and set it aside.
  2. Clean the carburetor: you can do this by using a carb cleaner and a clean cloth, removing any dirt, buildup, or debris. Be sure to thoroughly clean the carburetor passages and jet openings, as they are prone to clogging.
  3. Check the carburetor adjustments: Make sure that the carburetor is adjusted correctly. The carburetor controls the amount of fuel and air mixture that is supplied to the engine. If the carburetor is set too rich or too lean, it can cause the engine to stall or not start at all.
  4. Reassemble the air filter: After cleaning the carburetor, reassemble the air filter and make sure it is securely in place.
  5. Test start the chainsaw: Attempt to start your chainsaw after completing these steps. If it starts and runs without any issues, the plugged carburetor problem has been fixed.

Following these steps will enable you to fix a clogged carburetor in your chainsaw, returning it to optimal performance. To ensure proper engine operation and prevent future clogging, keeping the carburetor and air filter clean is necessary.

4. Inadequate Compression Fix

Inadequate compression can prevent a chainsaw from starting or cause it to run poorly. Following the steps listed below will help to fix the inadequate compression in a chainsaw.

  1. Check the cylinder and piston: The cylinder and piston are responsible for compressing the air and fuel mixture supplied to the engine. If the cylinder or piston is damaged or worn, it can cause the engine to have inadequate compression. Remove the cylinder and inspect it for any signs of damage. Replace the cylinder or piston if necessary.
  2. Check the cylinder and piston rings: The cylinder and piston rings are responsible for sealing the cylinder and ensuring that the air and fuel mixture is compressed correctly. If the rings are damaged or worn, they can cause the engine to have inadequate compression. Remove the cylinder and inspect the rings for any signs of damage. Replace the rings if necessary.
  3. Check the valves: The valves control the flow of air and fuel into and out of the engine. If the valves are damaged or worn, they can cause the engine to have inadequate compression. Remove the cylinder head and inspect the valves for any signs of damage or wear. Replace the valves if necessary.
  4. Check the valve springs: The valve springs are responsible for keeping the valves closed when they are not in use. If the springs are weak or broken, they can cause the valves not to close properly, resulting in inadequate compression. Replace the springs if necessary.
  5. Try starting the chainsaw: Start the chainsaw after these steps are taken. If it starts and runs smoothly, the compression problem is no longer an issue.

These steps will help repair inadequate compression in your chainsaw and restore its smooth operation. Regular maintenance and examination of the cylinder, piston, rings, valves, and valve springs can prevent compression issues and keep your chainsaw functioning optimally.

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( Licensed Chainsaw Professional )

Jake is a chainsaws expert with a wealth of knowledge and experience in the field. He is a licensed professional by the National Chainsaw Program, which attests to his skills and expertise in the safe and efficient use of chainsaws.