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Chainsaw Idles but won’t Rev. Tips from a Professional

One of the most common issues with a chainsaw is when it starts and idles fine but dies out just when the throttle is pressed. The fuel delivery system and its associated components might be at fault; hence, they must be checked individually. In this blog post, I will help you diagnose the underlying cause and enable you to solve the problem on your own.

Chainsaw idles but won’t rev:

If your chainsaw doesn’t rev up after idling, consider examining the air and fuel filters first, ensuring they are clean, not gummed up. Next, you need to adjust your carburetor’s adjustment screws and optimize the high-speed RPMs by turning the screws. Also, clean the carburetor if needed. If the problem remains, you may need to check for air leakage in the engine by performing a pressure/vacuum test.

In this article, I will explain why your chainsaw idles and won’t rev in more detail and why your engine stalls when you give it gas, including fixes.


Why does my 2-cycle Engine Stall when I Give it Gas?

If your two-stroke starts just fine, it means that the air-fuel mixture being delivered to it is adequate to initiate combustion and keep the engine running at no load.

However, as soon as the engine is loaded by applying throttle, it bogs down immediately, implying that the air-fuel charge isn’t enough to keep it running. Now, this may be due to any blockage in the fuel system components, or it may be due to an air leak.

It could also be possible that the carburetor is tuned to act as too rich or too lean in a high-speed setting. Sometimes, a vapor lock due to a preheated engine could also be causing this problem. Let’s investigate all these possibilities one by one.

Why does my Chainsaw Stall when I Give it Gas?

If your chainsaw stalls after giving gas, you should begin by inspecting its air filter, followed by the carburetor adjustment, cleaning the fuel filter and the fuel lines. Sometimes, you may need to conduct a vacuum test to check if there’s any air leakage in the engine assembly.

To troubleshoot your chainsaw, use the following step-by-step approach:

● Step 1: Air Filter:

We can easily inspect the air filter before examining the carburetor, which could be causing the chainsaw to stall. Like a fuel filter, it screens the ambient air before reaching the carburetor. When the filter becomes clogged, airflow is constricted, and the carburetor fails to produce the proper air-fuel combination, causing the engine to stall.

– Repair: Clean the Air Filter:

Your chainsaw’s air filter screen is located on the backside. Loosen the bolts that hold the air filter in place with a screwdriver. Pull out the filter and inspect it for dirt or deposits. I recommend using a soap and water solution if there isn’t a lot of dirt buildup.

If, after cleaning, it still does not appear to be in good condition, consider replacing it entirely. Air filters are inexpensive, and I recommend replacing them yearly to prevent engine problems.

● Step 2. Fuel Filter: 

Typically, debris accumulates on the fuel filter located within the fuel tank due to low fuel quality. As the name implies, a fuel filter filters the fuel so that the carburetor receives a clean and uncontaminated fuel charge. However, when it becomes clogged, the fuel passage to the engine is hindered, causing the engine to halt.

– Repair: Filter Inspection and Replacement:

Remove the chainsaw’s fuel cap and pour the gasoline into a different container to examine the fuel filter. After that, clean the filter using a dental pick or a thin metal rod. Examine the filter’s quality. If the filter still appears plugged with dirt, replace it with a new one. If it appears clean, keep it that way and move on to the carburetor.

● Step 3. Carburetor:

The carburetor needs to be tuned and properly serviced as a critical fuel system component. It essentially controls the air-fuel mixture’s composition. Hence, the carburetor must be inspected whenever a two-stroke engine undergoes performance-related issues.

– Fix: Carb Tuning:

The carburetor controls the fuel flow at idle, low-speed, and high-speed engine modes using the I, L, and H adjustment screws. Each screw controls the amount of fuel at that particular setting. E.g., the low-speed RPMs are controlled by the L screw. Tightening the screw restricts the fuel flow and increases the RPMs while loosening it decreases the engine’s RPMs at low speed. The same is true for I and H screws.

In our case, the engine starts up and runs fine at idle and low-speed settings. However, as the throttle is pressed for high speed, it begins to bog down. Hence, let’s troubleshoot the problem by tweaking the H screw first.

  • Tighten the H screw: Start your chainsaw’s engine and let it rev for a few minutes. Before pressing the throttle, tighten the H screw by using a screwdriver. After tightening by half a turn, press the throttle and notice if the high-speed RPMs have increased or not.
  • Note the 1st extreme point: The RPMs would certainly increase. If not, perform this procedure by loosening the screw instead. As the RPMs increase after tightening the H screw, keep tightening it until they begin to decrease. This is where the engine isn’t receiving enough fuel and begins to bog down. Please note this point (by remembering the number of turns it takes to reach).
  • Note the 2nd extreme point: Now, loosen the screw and keep the throttle pressed. The RPMs would continue to increase until a point is reached where they are at their maximum. Loosen it further until you notice the RPMs beginning to drop. Again, note this point’s location in terms of the number of turns.
  • Find the ideal spot: Note that the points determined above are the extreme locations. The operating point needs to lie somewhere in the middle. Adjust the screw until you reach that location. As you press the throttle at the new H location, the engine would run at an optimal high-speed setting and wouldn’t bog down like before.

– Fix: Carb Cleaning:

For cleaning your carburetor, I recommend using a carburetor cleaning liquid. If not available, you can use WD-40 instead. These liquids attack the gummy fuel deposits stuck within metal parts and ensure they are clean and debris-free.

  • Detach and disassemble the carb.: It is better to remove your carburetor to clean it more thoroughly. To detach it, first, remove the air filter. Followed by detaching the fuel lines and removing the links holding them in place.
  • Clean the bowl: After removing the carburetor, detach the bowl nut and spray the cleaner liquid on its interior. Remove any stale fuel present in the bowl. Also, spray the cleaner liquid on the bowl nut to dislodge debris.
  • Clean the interior. Spray the carburetor cleaner on the butterfly valve and the remaining interior parts. You can check that the jets are unclogged by noticing the cleaner fluid coming from the other end. After you are done, reattach the carburetor and assemble it back on the chainsaw.

● Step 4. Air Leakage:

The engine’s seals and gaskets are liable to get worn out over time, and once damaged, they may allow a two-way flow of the air-fuel charge across them. As the air leaks out of the engine, it reduces its compression, and the engine begins to bog down.

The air leakage is less likely to occur when your engine starts perfectly. However, even in that situation, it is possible as the leakage effect gets aggravated when the throttle is pressed. This is because, at high RPMs, increased thermal expansion causes more air to leak out of the opening in the gaskets and crank seals.

Fix: Pressure Test:

The pressure test locates the point where the air is leaking from. Once identified, it can be fixed. Usually, the leakage sites are the crank seals and the head gaskets. I recommend purchasing a testing kit to perform a pressure/vacuum test yourself. It contains a manual pump fitted with a pressure gauge.

The pump’s hose is connected at the spark plug’s location, and the engine is pressurized. If the pressure begins to fall, this confirms a leak. The leak’s location can be determined by spraying some soap water at the suspected locations (such as seals and gaskets). If the air leaks, bubbles will be formed at these points

● Step 5. Vapor Lock:

Vapor lock is a condition when the engine cannot draw enough fuel from the tank due to excessive buildup of fuel vapors within the fuel lines. This condition occurs when the engine becomes overheated either due to use at wide-open throttle (WOT) or being kept open in the sun. The engine might start, but as the throttle is pressed, it would not receive enough fuel to keep it running.

– Fix: Open the Cap:

The solution to a vapor lock is relatively simple. Keep your engine off and open the fuel tank’s cap for a while. Let the vaporized fuel escape from the tank and cool down the engine. Ensure the tank vents aren’t plugged to allow safe passage to the vapors when in use.

Can a Seized Chainsaw be Fixed?

A seized chainsaw can be fixed if the engine or its components aren’t permanently damaged. If a chainsaw was seized due to a pull chord or flywheel damage, it probably could be repaired. If other engine components are damaged, it probably can not be fixed in most cases.

Engine seizure is a term that commonly refers to when the engine is unable to deliver power due to the pistons getting jammed in the cylinder. This condition typically occurs due to extreme operating conditions, i.e., using the chainsaw at wide-open throttle (WOT) for an extended period, or overheating it excessively with a lean fuel mix. Typically, engine seizures render the chainsaw useless and sadly cannot be fixed in most cases.

The term seizure is also used when a chainsaw cannot start due to damage to the flywheel or pull cord mechanism. This can surely be fixed. To begin with, you need first to inspect the flywheel and its vanes for signs of damage. Also, check if the flywheel can rotate freely along its shaft.

Next, examine the pull cord mechanism. Check if its spring is loaded correctly and the pull cord isn’t tangled. If you see it getting stuck or damaged in any way, I recommend replacing the pull cord mechanism with a new one. It is quite cheap and readily available from a local dealer or online.

Regular Chainsaw Maintenance

Importantly, the longevity and optimal performance of your chainsaw highly depend on constant servicing and maintenance. Chainsaws are subjected to wear and tear, just like any other tool, primarily when used regularly.

Routine check-ups guarantee a smoothly running chainsaw that is effectively cutting. Moreover, it averts problems that could cause downtime, thus affecting your productivity in other tasks.

• Investigating Engine-related Issues

When a chainsaw displays engine problems, the factors you must consider revolve around three main areas. These are fuel, spark, and air.

Regularly inspect these three areas to detect potential issues on time, and address them immediately. Constant checks can save you countless damage that might incur massive repair costs.

• Pre-check Procedures

Before performing any troubleshooting procedures, there are essential basic checks you must undertake. Notably, these include testing the chainsaw’s engine compression and checking the quality and mixture of the fuel.

Also, inspect the state of the fuel filter and check if there are any blockages in the fuel supply pickup and hose. These are fundamental tests that could help you identify the chainsaw’s issue before proceeding to more advanced troubleshooting steps.

• Air Filter and Muffler Check

The air filter and the muffler are key parts of the operational system of the chainsaw and should be checked.

A blocked air filter or muffler can compromise the airflow into the engine, causing a decrease in performance. Additionally, the muffler spark arrestor screen should be checked and cleaned if any debris is observed.

• Spark Plug Inspection

In your troubleshooting process, checking the spark is an important step. If you find the chainsaw lacking a spark, the spark plug could be a culprit. Typical problems associated with the spark plug include carbon build-up, damage, or wear. A faulty spark plug can cause difficulties when starting your chainsaw or other performance issues.

• Adjusting the Carburetor Settings

If your chainsaw still poses problems after taking the above steps, the next step should be adjusting the carburetor settings. The carburetor controls the air/fuel mixture that feeds into the engine. By tweaking its settings, you can regulate how much fuel gets mixed with air, impacting engine performance.

• Recognizing Compression Issues

Hard starting has been known to be a leading indicator of compression problems. Similarly, low compression will also raise red flags. Air leaks are usually common around the crankshaft seals, a crucial area to inspect if you suspect compression issues.

• Seeking Assistance

Using the chainsaw’s owner’s manual for specific instructions is highly recommended, especially when undertaking repairs or troubleshooting mechanically related issues. However, don’t shy away from professional assistance when handling chainsaw problems.

If you are not comfortable with repairs, get professional help to avoid the risk of inflicting more damage on the chainsaw.

The University of Missouri’s Extension program provides useful information on chainsaw operation and safety that could be invaluable to all chainsaw owners.

Always remember chainsaw maintenance and servicing is an ongoing process. Regular check-ups will reduce the probability of encountering issues, ensure optimal performance, and elongate your chainsaw’s lifespan.

• Chainsaw Starting up Amidst Challenges

This whole episode started with an unpredictable chainsaw issue. A Johnsseredv 2054 model is generally a reliable and trusted tool. However, with some issues experienced recently, its credibility was brought into question.

• Chainsaw Failing to Rev-Up

The chainsaw was starting up but failed to rev up and stalled immediately when the throttle was activated. There was no issue with the initial start, but the issues surfaced soon after. The chainsaw would simply stall and shut down, making the job indeed frustrating.

• Attempts to Get Chainsaw Running

The huge number of attempts to start the chainsaw was another red flag, screaming that there was indeed an issue. Approximately fifty attempts were made each time before the chainsaw began to exhibit any form of normal performance, a warm-up period much longer than typical.

• The Chainsaw Repair Episode

Upon realizing these issues, Tia Eulb took the fundamental step of sending the chainsaw for repair. Spending around 50 on the repair seemed a worthwhile investment, considering the importance of the tool.

• Post Repair Scenario

Post repair, the chainsaw appeared to function fine, but not for long. It worked smoothly only for the duration of one full tank of fuel. After that, it was back to the old issues. This raised some valid questions about the longevity and the quality of the repairs that were made.

• Misuse of Hydraulic Oil

Gradually, the investigation led to the identification of the core problem – it was not the chainsaw’s manufacturing fault, nor a mechanical error.

Rather, it was a minor mix-up causing significant disruption. The chainsaw problems were due to the misuse of hydraulic oil in the petrol instead of the recommended 2-stroke oil.

• The Culprit: Wrong Oil Type

The Johnsseredv 2054 model, just like many other chainsaws, requires 2-stroke oil for optimal performance. A mix of hydraulic oil instead caused the issues encountered involving start-up, revving up, and the overall poor performance which led to unnecessary costs.

• Mitigating Similar Issues

Based on my personal experience, it’s crucial to double-check the type of oil you’re using in your chainsaw. Reading the user manual or referring to a legitimate guide for chainsaw use will save you from most chainsaw problems. The University of Missouri Extension’s guide can be a good starting point.

• Johnsseredv 2054: Generally Reliable Model

Finally, it merits mentioning that the Johnsseredv 2054 chainsaw model is generally a reliable tool, and this was an extremely rare scenario. Such an issue does not tarnish the reputation of the model at large. Errors involving incorrect oil types could inconvenience users of any chainsaw model.

• Professional Recommendation

I recommend always ensuring that your chainsaw is properly maintained and serviced. Verify the type of oil you’re using in your chainsaw.

Treat all tools with respect and use them correctly, as per the manufacturer’s guidelines. This will not only prolong their service life but also ensure that users get the best performance out of them.

• Checking the Spark Plug

Your first step should always involve closely checking the spark plug. Often, a worn-out or dirtied spark plug could be the culprit behind your engine stall at full throttle.

Any signs of damage or heavy fouling are profound indications that it’s time for a change. Remember, for a smooth and efficient running engine, pristine spark plugs are crucial.

For more information on how to clean or replace spark plugs, check out this guide by the Oregon State University Extension Service: Link to the appropriate resource.

• Inspecting the Ignition System

In addition to inspecting your spark plug, you should also examine the entire ignition system. Specifically, focus on the ignition coil and the spark plug wire. The abrupt disruption of the spark delivery is often the effect of some faults or loose connections within the ignition system.

Throughout my years of experience, I’ve consistently found the majority of ignition faults are due to aging parts or poor connections. To avoid this, make sure these components are regularly maintained and properly connected.

• Verifying Throttle Functionality

Another crucial point to check is the throttle trigger and throttle linkage. An issue with either of these could impede the engine’s ability to reach full throttle. If the throttle is sticking or not engaging properly, it could cause a malfunction.

From my experience, a quick inspection and proper lubrication of these components can usually rectify most issues.

• Examining the Fuel Cap and Vent

Indeed, a small part, like a fuel cap, can influence your engine’s performance. If the fuel tank cap and vent aren’t working correctly, it might cause issues like vapor lock and subsequent engine stalling. The main function of these two parts is to ensure appropriate airflow and pressure release.

Pro tip: A malfunctioning cap is often characterized by difficulties in removing it or irregular pressure issues. Always ensure that the cap is releasing pressure properly when untwisting it.

• Evaluating the Fuel Pump

A faulty or weak fuel pump might fail to deliver the necessary fuel quantity to the engine at high throttle. Therefore, as part of your comprehensive check-up, inspect the fuel pump and its connections. Any seemingly minor issues here could potentially cause severe performance flaws.

If you’re not experienced in this area, I recommend consulting a professional or visiting an authorized service center.

• Reviewing the Cylinder and Piston Conditions

Lastly, check the state of the engine’s cylinder and piston. Any damage or excessive wear signs in these areas will undoubtedly affect your engine’s performance at high throttle.

Needless to say, damaged pistons or cylinders usually require professional help. Consequently, if you suspect any anomalies here, reach out to a trusted mechanic immediately.

In conclusion, this maintenance checklist will assist you in identifying and rectifying issues causing your engine to stall at full throttle.

It’s wise to conduct these checks periodically to maintain your engine’s optimal performance. However, if you’re not confident in performing any of these actions, it’s best to consult a professional.

Remember, prevention is always better than cure when it comes to engine maintenance. Thus, regularly performing these checks can help you avoid costly repairs in the future.

For more information on maintaining small engines, review this guide provided by the PennState ExtensionLink to the appropriate resource.

• The Importance of Spark Plug Maintenance (Step 1)

The first step is ensuring that the spark plug of your chainsaw is functioning correctly. Frequently check your spark plug to avoid any problems, such as ignition malfunction or engine overheating. This is one of the simplest yet crucial parts of your chainsaw that should always be checked before use.

In the case of any damage, ensure to replace it immediately. For a detailed guide on how to check or replace your chainsaw’s spark plug, refer to this Comprehensive Guide from Penn State Extension.

• Maintaining Your Fuel Lines (Step 2)

Following the spark plug inspection, the fuel lines should be the next thing you inspect. Look out for any cracks or leaks that could cause a decline in the chainsaw’s performance or, worse, result in a dangerous fuel leak.

This inspection should happen routinely. If you discover any damage, replace the fuel lines as soon as possible.

• Clean the Exhaust Port and Muffler (Step 3)

Keeping the exhaust port and muffler clean is paramount to maintaining an efficient and safe chainsaw. This task ensures unobstructed airflow and boosts the overall chainsaw’s performance. Regularly clean this part of your chainsaw to keep it in top-notch condition.

• Check the Ignition Coil (Step 4)

The ignition coil is another critical component of a chainsaw and should be checked regularly for any signs of damage.

A faulty ignition coil can hinder the chainsaw’s performance, making it difficult to start or causing it to stall unexpectedly. If you find any signs of damage or malfunction, be sure to replace it immediately.

• Throttle Trigger Inspection (Step 5)

Aside from the internal components, it’s also important to ensure that the throttle trigger is functioning correctly and that it is adjusted properly. Incorrect adjustment can lead to dangerous situations or faulty operations, so routine checking is necessary.

• Engine Compression Test (Step 6)

Another crucial part of chainsaw maintenance is performing a compression test. This helps verify the health and functionality of your chainsaw engine.

Essential tools such as a compression tester can quickly be used for this. A detailed guide on how to perform a chainsaw engine compression test can be found on the Instructables Website.

• Ensuring Correct Fuel Mixture Ratio (Step 7)

Fuel mixture ratios vary among chainsaw models. It’s important to ensure that the mixture in your fuel tank is precise for your specific chainsaw. This can greatly affect the chainsaw’s performance; thus, always ensure to follow the manufacturer’s recommendations for the correct ratio.

• Cleaning the Fuel Tank (Step 8)

Regularly inspect and clean any dirt or debris from the fuel tank. A dirty or blocked fuel tank can hinder the chainsaw’s performance. This task is as essential as maintaining any other part of your chainsaw and should be part of your routine inspection and cleaning.

• Professional Assistance (Step 9)

If you’ve gone through all the steps but the issue persists, it may be time to seek professional help. Trained technicians have the skills and resources necessary to diagnose the problem accurately and execute the required repairs.

Chainsaw maintenance and repair can be a complex task and it’s always recommended to seek professional help when in doubt. Further resources regarding this can be found on the official USDA website.

Cleaning the Spark Arrestor

In my recent work on maintaining a chainsaw, one task on the agenda was inspecting and cleaning the spark arrestor. Over time, this component can accumulate soot or carbon deposits and need to be cleaned.

Although the spark arrestor only had a small amount of carbon buildup, it was still necessary to disassemble and clean it regularly to ensure it was working correctly. This process should be an integral part of chainsaw maintenance.

Here’s a descriptive guide about spark arrestors from Iowa State University Extension and Outreach, which I often refer to for contextual knowledge.

• Unmixed Fuel Trial

After cleaning the spark arrestor, the chainsaw still wouldn’t function properly. The next step was to test the chainsaw with straight, unmixed fuel.

Interestingly, the chainsaw would not shut off, despite the ignition switch being toggled to OFF. This anomaly was quite perplexing, as the chainsaw should respond readily to the ignition switch.

• Revisiting Fuel Choice

Upon reviewing this peculiar issue, I realized a potential error I had made while refueling the chainsaw. It seems likely that I had indeed used fuel without considering the ethanol content.

Using pure fuel without ethanol may have been the mistake that caused the chainsaw not to operate correctly. If you are new to chainsaw maintenance, always remember that the right fuel is crucial.

• Switching to A 50:1 Fuel Mix

To rectify the previous mistake, I decided to switch over to a regular 50:1 fuel mix. But before proceeding with the switch, I cleaned the tank, fuel lines, and carburetor thoroughly to ensure residual unmixed fuel did not interfere with the operation.

Despite these efforts to eliminate the problem, the chainsaw, frustratingly, merely idled. When any normal throttle was applied, it would promptly die out.

• Exploring Professional Help

Scenarios like these can be incredibly tricky and exhausting. Therefore, I sought professional advice from a saw shop. Their recommendation was to replace the carburetor. That is one solution, but I felt further investigation was necessary.

• Rebuilding the Carburetor

Having already gone through the process of rebuilding the carburetor previously, I was skeptical about replacing it outright. It is plausible that replacing the carburetor would rectify the issue, but it also felt that the issue lay elsewhere.

• Checking the Impulse Line

In reflecting upon my experience, an area that I overlooked was the impulse line. It plays a critical role in ensuring fuel is pumped into the carburetor.

If it is partially clogged, this could result in not enough fuel reaching the carburetor, regardless of the mixture used. This could potentially explain why the chainsaw merely idles and dies out when normal throttle is applied.

It’s crucial to consider each part of the chainsaw and its potential impact on the overall functionality. In retrospect, not checking the impulse line sooner was an oversight. It’s a reminder that sometimes, the most well-used machines require the most complex troubleshooting.

Continually learning is an integral part of my experience in chainsaw maintenance. The chainsaw, like any mechanical tool, can teach us more about our patience and investigative skills than we might anticipate.

• The Importance of Accurate Diagnosis

Accurately diagnosing mechanical issues is often a process of elimination. It requires a methodical approach and a detailed understanding of the device’s various components.

This story tells us the importance of patience, the correct method of investigating the root cause, and open-mindedness to various solutions, even if they seem unconventional. It’s a learning that extends beyond chainsaw maintenance.

Remember, don’t be disheartened when a problem seems too complex or when the initial solutions don’t work out. It’s okay to take a step back, reassess, and explore other potential issues. A recommendation from my experience is to keep encouraging your curiosity and troubleshooting spirit.