Chainsaw Cuts Out When Hot, what is the reason and how to fix this?


Most homesteaders prefer using gas-powered chainsaws due to their high power and better workability on hardwood. However, such chainsaws require frequent maintenance due to their mechanical parts and are prone to witness ignition and fuel supply problems. One of the most common problems that homeowners witness is a chainsaw engine dying out when hot. There can be various causes behind this, and we shall investigate them in this blog post.

Chainsaw cuts out when hot, what is the reason and how to fix this:

  • Clogged Spark Arrestor: Examine the spark arrestor screen for carbon deposits and remove them using a brush or a propane torch.
  • Blocked Fuel Filter: The fuel filter in your tank might be clogged with deposits and needs to be replaced.
  • Dirty Air filter: Clean the air filter from any form of dust or debris.
  • Restricted Carburetor: Use a carburetor cleaner liquid to dislodge any fuel deposits in the carburetor.

Some additional steps that can help solve the problem:

  • Vapor lock: Clean the fuel cap of your chainsaw to allow proper venting of gasoline vapors.
  • Faulty ignition system: Check the spark plug electrodes and test the ignition coil to see if your engine’s ignition system works.

Most chainsaws use a two-stroke engine to produce power. For such engines, timely maintenance is always the key to prevent any hitches since they don’t have a sophisticated fuel delivery system as present in most automobiles. Whenever such engines face difficulty in starting, or when they die out after starting, then in most cases, there’s a problem with the fuel supply system. The fuel supply consists of fuel and air filters, a fuel tank, and a carburetor. Clogging and restrictions in these delivery channels due to degraded fuel can create difficulties for the engine to start. Occasionally, some hitches in the ignition system can also cause engine-related problems. This may include a bad spark plug or a faulty ignition coil.

We recommend reading the entire blog post for getting a thorough insight regarding typical engine-related problems and their fixes.

Causes and Fixes of a Chainsaw Dying out When Hot

There can be various factors causing the chainsaw to stall after getting started. You should investigate these factors one by one and check if that solves the problem or not. The procedure is laid out in the listed sections.

1. Clogged Spark Arrestor:

It would be best if you began the troubleshooting by starting from the most straightforward fixes. In this case, you should probably check from the spark arrestor screen first. The spark arrestor screen is a metallic wire mesh that prevents the spark from exiting the muffler. Due to prolonged exposure to sparks, the screen gets clogged with carbon deposits.

Use a screwdriver to remove the screws and check the arrestor for soot/carbon deposits. If it is clean, you don’t need to do anything, but if it appears clogged, you should consider cleaning it or, if not possible, replacing it with a new one.

– Fix: Cleaning the Arrestor:

To clean the spark arrestor, you can use a wire brush to dislodge any deposits of soot. If available, you may also a propane torch to fire up the arrestor’s mesh and clean it from soot.

Put the arrestor screen back on after cleaning. If it still doesn’t solve the issue, we shall move to the next troubleshooting step. i.e., a clogged fuel filter.

2. Clogged Fuel Filter:

Due to poor fuel quality, deposits tend to form on the fuel filter situated inside the fuel tank. As the name suggests, it filters the fuel so that a clean and uncontaminated gasoline charge is supplied to the carburetor. However, when it gets clogged, the flow of gasoline to the engine is affected, thus causing the engine to stall.

– Fix: Checking and Replacing the Fuel Filter:

To check the fuel filter, open the fuel cap of your chainsaw and take some gasoline out of it into a separate container. Next, use a dental pick or a thin metal rod to filter out the tank. Check the quality of the filter. If It appears clogged, you should buy a new filter and replace the old one. If it seems clean, leave it as it is and consider checking the carburetor and the air filter for restrictions.

3. Dirty Air Filter:

Before we check the carburetor, it is easy to examine the air filter first, which might be causing the chainsaw to die out. Just like a fuel filter, it filters the ambient air before it reaches the carburetor. When it gets dirty, the carburetor doesn’t make the proper air-fuel mix, and hence the engine faces trouble starting.

– Fix: Cleaning the Air Filter:

The air filter screen is situated behind your chainsaw. Use a screwdriver to loosen the fasteners securing the air filter. Take the filter out and check it for dirt/deposits. If the dirt isn’t much, you can clean it using a soap and water solution. However, if it doesn’t look in good shape even after cleaning, consider replacing it altogether. Air filters are pretty cheap, and you should replace them every once a year to avoid problems with your engine.

4. Restricted Carburetor:

One of the leading causes behind the stalling of small engines is a restricted carburetor. A carburetor formulates the air-fuel mixture, which is supplied to the engine for combustion. Sometimes, when fuel is stored for longer durations in the tank, its quality degrades as it forms white deposits in the fuel lines. These deposits can clog the jets of a carburetor and affect the flow of fuel to the engine. To unclog the restricted carburetor, carburetor servicing needs to be performed.

– Fix: Carburetor Cleaning:

For small engines such as those in a chainsaw, carburetor cleaning can be performed with much convenience, considering fewer mechanical parts. All you need is a regular carburetor cleaning spray. The steps are provided as follows:

  • Step 1: Locate the carburetor: First, you need to locate the carburetor in your chainsaw. It is generally present behind the air filter. So, if you’ve removed the air filter earlier, you can easily access the carburetor.

You can consider removing and then cleaning it, or you can also clean it without detaching it entirely from the chainsaw, depending on your skill level while performing DIY work. Nevertheless, we recommend not detaching it entirely as it’s more convenient.

  • Step 2: Detach the bowl and clean it: You should begin by removing the bowl nut from the carburetor and detaching the bowl. In most cases, the bowl may contain stale fuel and its deposits. Hence, it should be cleaned from any deposits and old fuel.
  • Step 3: Spray the cleaner on the interior: Next, you should spray some carburetor cleaner liquid on the inner sections of the carburetor. Don’t forget to clean the bowl nut, which is a jet and has greater chances of getting clogged. Once you see the spray coming out of the other side of a jet, you can know that any debris has been dislodged.

After you’ve finished cleaning, reassemble everything that was removed.

Some Additional Causes of a Chainsaw Dying Out

If the steps mentioned in the above section do not solve the issue, you should try addressing the following fixes.

5. Vapor Lock:

The fuel cap in your chainsaw has vent holes that allow the vapors to escape and maintain the atmospheric pressure inside the gas tank. These vent holes often get clogged due to dust and oil/fuel deposits. As a result, gasoline vapors get trapped in the gas tank. This upsets the pressure inside the tank, thus making it difficult for the carburetor to draw sufficient fuel.

– Fix: Unclog the Vent Holes:

The solution to this problem isn’t a tricky one. You need to inspect the fuel tank’s cap to see if the holes are plugged or not. If they appear restricted, use a metal wire to clean them from the debris. Place the fuel cap back on and see if that solves the problem.

6. Bad Ignition System:

If the issue persists after trying everything from the above steps, it is almost sure that your ignition system is faulty. An old or worn-out spark plug might be causing this issue, or the ignition coil might not be working.

– Troubleshooting and Fixing:

To troubleshoot this, remove the spark plug from your engine and check its electrodes. If the carbon build-up is significant and the spark plug doesn’t seem in good shape, consider replacing the spark plug.

If that doesn’t fix the issue or the spark plug is in good shape, your ignition coil is undoubtedly defective. You can use an ignition tester to check if it is producing any voltage. This can be done while attaching the tester terminals to the terminals of the coil while the engine is running—no spark indication by the tester points towards a defective ignition coil.

Final Remarks:

By and large, most engine problems can be prevented by performing timely maintenance of your engine’s components. Most homeowners tend to leave the gasoline in their tanks as it is when the device is no longer in use. Gasoline sits in a tank for a long and develops white sticky deposits that make it prone to block the fuel supply passages. As a result, your engine doesn’t start or doesn’t stay running for long.

We always recommend that you should avoid storing gasoline in your fuel tank for a long. In case it is unavoidable, always add a fuel stabilizer liquid that prevents its quality from degrading. Furthermore, don’t forget to perform timely maintenance of your chainsaw by keeping the filters and the plugs clean and deposit-free. We aim to provide you with the insight and knowledge to equip you better to solve such problems independently.

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