Professional Advice on Chainsaw Stalled

Professional Advice on Chainsaw Stalled

Chainsaw Stalled? One of the most typical problems with a chainsaw is that it starts and idles normally but dies when the throttle is applied. Why? Possibly because the gasoline distribution system and its accompanying components might be faulty, they must be examined independently. In this ‘Advice on Chainsaw Stalls‘ article, I will try to help you in diagnosing the underlying reason and resolving the problem on your own.

Free manuals and carburetor manuals are available from this website.

Chainsaw Idles But Will Not Rev

If your chainsaw does not start after idling, check the air and fuel filters to ensure they are clean and not clogged. Then, by rotating the adjustment screws on your carburetor, you may optimize the high-speed RPMs. If necessary, clean the carburetor. If the problem persists, you may need to do a pressure/vacuum test to look for air leaking in the engine.

Chainsaw Idles But Will Not Rev

In this post, I’ll go over why your chainsaw idles and won’t rev, as well as why your engine stalls when you give it gas, and how to fix it.


Why does my two-cycle engine stall when I start it?

If your two-stroke starts easily, it signifies that the air-fuel combination provided to it is sufficient to commence combustion and maintain the engine running at idle.

However, when the engine is loaded by providing throttle, it instantly bogs down, signaling that the air-fuel charge is insufficient to keep it going. This might be caused by an obstruction in the fuel system components or by an air leak.

It’s also plausible that the carburetor is adjusted to run too rich or too low at high speeds. A vapor lock caused by a warmed engine might also cause this problem. Let’s look into each of these ideas one by one.

Why does my chainsaw stall when I give it gas?

If your chainsaw stalls after you give it gas, check the air filter first, then adjust the carburetor and clean the fuel filter and fuel lines. A vacuum test may be required to determine whether or not there is any air leakage in the engine assembly.


Use the following step-by-step procedure to troubleshoot your chainsaw:

1. Air Filter

Before inspecting the carburetor, which might be causing the chainsaw to stall, we can quickly inspect the air filter. It screens the flow of air before it reaches the carburetor in the same way as a fuel filter does. When the filter clogs, airflow is restricted and the carburetor fails to create the necessary air-fuel mixture, causing the engine to stall.

2. Clean the Air Filter

The air filter screen on your chainsaw is placed on the back or top. Using a screwdriver, loosen the nuts that hold the air filter in place. Remove the filter and check it for dirt or deposits. If there isn’t a lot of dirt accumulation, I recommend utilizing a soap and water solution.

If it still doesn’t appear to be in excellent shape after cleaning, consider replacing it totally. Air filters are affordable, and I recommend replacing them once a year to keep your engine running smoothly.


3. Fuel Filter

Due to poor fuel quality, debris typically collects on the fuel filter placed within the gasoline tank. A fuel filter, as the name indicates, filters the gasoline so that the carburetor receives a clean and uncontaminated fuel charge. When it becomes clogged, however, the fuel path to the engine is obstructed, causing the engine to stall.

4. Filter Inspection and Replacement

Remove the fuel cap from the chainsaw and pour the gasoline into a separate container to inspect the fuel filter. The filter should then be cleaned using a dental pick, thin metal rod or suchlike (be careful not to do any damage to the chainsaw. Check the filter’s quality. Replace the filter if it still looks to be clogged with dirt. If it seems clean, leave it alone and go to the carburetor.

5. Carburetor

As a crucial component of the gasoline system, the carburetor must be adjusted and maintained. It essentially regulates the ratio of the air-fuel combination. As a result, if a two-stroke engine exhibits performance concerns, the carburetor must be examined.

6. Carburetor Tuning

Using the I, L, and H adjustment screws, the carburetor regulates fuel flow in idle, low-speed, and high-speed engine modes. Each screw regulates the amount of gasoline at that specific position. The L screw, for example, controls the low-speed RPMs. Tightening the screw inhibits fuel flow and raises RPMs, while loosening it lowers RPMs at low speeds. The same may be said for I and H screws.


In our situation, the engine starts and operates smoothly at idle and low speeds. When the throttle is squeezed for high speed, though, it tends to bog down. As a result, let’s start troubleshooting by adjusting the H screw.

  • Tighten the H screw: Start the engine on your chainsaw and rev it for a few minutes. Tighten the H screw with a screwdriver before pushing the throttle. Press the throttle after tightening by half a turn to see if the high-speed RPMs have increased or not.
  • Extreme point 1: The RPMs would very probably increase at the first extreme point. If this is not the case, release the screw instead. Tighten the H screw as the RPMs grow after tightening it until they begin to decrease. This is the point at which the engine begins to bog down due to a lack of gasoline. Please keep this in mind (by remembering the number of turns it takes to reach).
  • Extreme point 2: Next, Loosen the screw while keeping the throttle pushed. The RPMs would continue to grow until they hit their limit. Loosen it further more till you observe the RPMs dropping. Take note of the placement of this point in terms of the number of turns once more.
  • Find the best setting: It should be noted that the points determined above are the most extreme positions. The functioning point must be located somewhere in the center. Adjust the screw till you get to that point. When you apply the throttle at the new H position, the engine will operate at an ideal high-speed setting and will not bog down as it did previously.

Carburetor Cleaning

I recommend utilizing a carburetor cleaning solvent to clean your carburetor. If WD-40 is not available, you can substitute it. These solutions tackle the gummy fuel deposits that have been lodged within metal components, ensuring that they are clean and debris-free.

  • Remove and disassemble the carburetor: It is preferable to remove your carburetor to completely clean it. Remove the air filter first to separate it. The gasoline lines are then disconnected and the connections that keep them in place are removed.
  • Clean the bowl: After removing the carburetor, unscrew the bowl nut and spray the interior with cleaner liquid. Remove any stale fuel from the basin. Spray the cleansing liquid over the bowl nut to remove debris as well.
  • Clear out the inside. Spray the carburetor cleaner on the butterfly valve and any other inside components. Check sure the jets are clear by seeing the cleaner fluid flowing from the opposite end. After you’re finished, reconnect the carburetor and reassemble the chainsaw.

Leakage of Air

The seals and gaskets in the engine are prone to wear over time, and if broken, they may enable a two-way passage of the air-fuel charge over them. As air leaks from the engine, compression is reduced, and the engine begins to bog down.

When your engine starts flawlessly, air leakage is less likely to occur. Even in such case, it is possible since the leakage effect is worsened when the throttle is down. This is because higher thermal expansion causes more air to leak out of the openings in the gaskets and crank seals at high RPMs.


Pressure Test

The pressure test determines where the air is seeping. It is possible to repair it after it has been detected. Crank seals and head gaskets are common leakage points. I recommend getting a testing kit to run your own pressure/vacuum test. It has a manual pump with a pressure gauge.

The pump’s hose is attached at the site of the spark plug, and the engine is pressured. If the pressure begins to drop, this indicates a leak. The location of the leak can be detected by spraying soap water at the suspicious spots (such as seals and gaskets). Bubbles will occur at these spots if the air leaks.

Vapor Lock

Vapor lock occurs when the engine is unable to draw sufficient gasoline from the tank owing to an excessive accumulation of fuel vapors within the fuel lines. This situation arises when the engine overheats as a result of using the engine at full throttle (WOT) or leaving it open in the sun. The engine may start, but it will not receive enough gasoline to maintain running as the throttle is squeezed.

Open the Cap

The answer to a vapor lock is straightforward. Turn off your engine and leave the gasoline tank cap open for a time. Allow the evaporated gasoline to exit the tank and cool the engine. When in use, make sure the tank vents are not clogged to allow safe passage of the vapors.


Is it possible to repair a seized chainsaw?

If the engine or its components are not irreparably damaged, a seized chainsaw can be repaired. If a chainsaw became seized owing to a faulty pull cord or flywheel, it could most likely be rectified. In most circumstances, if additional engine components are damaged, the engine cannot be repaired without a complete engine rebuild.

Engine seizure is a word used to describe when an engine is unable to provide power because the piston has become stuck in the cylinder. This issue is often caused by harsh operating circumstances, such as running the chainsaw at full throttle (WOT) for an extended period of time or overheating it with a lean fuel mix (none or too little 2 stroke oil added). In most situations, engine seizures leave the chainsaw inoperable and cannot be repaired.

When a chainsaw cannot start owing to damage to the flywheel or pull cord system, the term seizure is used. This is undeniably fixable. To begin, visually check the flywheel and its vanes for signs of damage. Check to see if the flywheel may freely revolve along its shaft.

Examine the pull cord assembly next. Check that the spring is properly loaded and that the pull cord is not twisted. If you see it becoming stuck or damaged in any way, I recommend replacing the pull cord mechanism. It is reasonably priced and readily accessible from a local dealer or online.


Free manuals and carburetor manuals are available from this website.

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