Carburetor for Poulan Pro Chainsaw (5 Expert Fixes You Must Know)

Let’s get that Poulan Pro chainsaw roaring again! A sputtering, stalling, or simply non-starting Poulan Pro chainsaw often points to a carburetor issue. Carburetors, those intricate little fuel-air mixing devices, are notorious for gumming up, especially if the saw sits unused for extended periods. I’ve seen it countless times in my years of working with chainsaws, both professionally in logging and just helping neighbors with their tree trimming. The good news is, with a little know-how, some basic tools, and a systematic approach, you can often diagnose and fix carburetor problems yourself. This guide will walk you through five expert fixes, designed to get your Poulan Pro chainsaw back in action.

Understanding Your Poulan Pro Chainsaw Carburetor

Before diving into the fixes, let’s establish a basic understanding of what a carburetor does and why it’s so crucial.

What is a Carburetor?

Simply put, a carburetor’s job is to mix fuel and air in the correct proportion to create a combustible mixture for the engine. It’s a relatively simple mechanical device, but its precise operation is vital for engine performance. In a two-stroke engine like the one found in most Poulan Pro chainsaws, the carburetor needs to provide the right fuel-air mix at different engine speeds and loads.

Why Carburetors Get Clogged

The primary culprit behind carburetor problems is old fuel. Modern gasoline contains ethanol, which can attract moisture and break down over time, forming varnish and gummy deposits. These deposits clog the tiny passages and jets within the carburetor, disrupting the fuel-air mixture. Leaving fuel in the chainsaw’s tank during storage is a surefire way to invite carburetor issues.

Key Carburetor Components

To effectively troubleshoot, familiarize yourself with these key components:

• Fuel Inlet: Where fuel enters the carburetor from the fuel tank.
• Fuel Filter: A small filter that prevents debris from entering the carburetor.
• Needle Valve: Controls the flow of fuel into the float bowl.
• Float Bowl: A small reservoir that holds a supply of fuel.
• Main Jet: Meters the fuel flow at higher engine speeds.
• Idle Jet: Meters the fuel flow at idle speed.
• Choke Valve: Restricts airflow to enrich the fuel mixture for starting.
• Throttle Valve: Controls the amount of air entering the engine, thereby controlling engine speed.
• Adjustment Screws (H and L): High-speed (H) and Low-speed (L) adjustment screws fine-tune the fuel-air mixture.

Expert Fix #1: The Fresh Fuel Flush

This is often the simplest and most effective first step. I’ve seen many “dead” chainsaws revived simply by replacing old fuel with fresh fuel.

Why it works: As mentioned earlier, old fuel is the enemy. A fresh fuel flush removes the gunk and varnish that can clog the carburetor.

Step-by-Step Guide:

1. Drain the Old Fuel: Carefully drain all the old fuel from the fuel tank into a suitable container. Dispose of the old fuel properly. Don’t just dump it down the drain!
2. Inspect the Fuel Filter: Locate the fuel filter inside the tank, usually attached to the end of the fuel line. Pull it out carefully. If it’s visibly dirty or clogged, replace it. A clogged fuel filter restricts fuel flow and can mimic carburetor problems. I recommend replacing the fuel filter annually, regardless of its appearance. They’re cheap insurance against fuel-related issues.
3. Prepare Fresh Fuel: Mix fresh, high-quality gasoline with the correct ratio of two-stroke oil, as specified in your Poulan Pro chainsaw’s manual. This is usually a 50:1 ratio (50 parts gasoline to 1 part oil). Use a fuel stabilizer in your fuel mixture, especially if you don’t use the chainsaw frequently. Fuel stabilizer helps prevent the fuel from breaking down and forming deposits.
4. Fill the Fuel Tank: Fill the fuel tank with the fresh fuel mixture.
5. Prime the Carburetor: Press the primer bulb several times until it fills with fuel. This helps draw fuel into the carburetor.
6. Attempt to Start: Follow your chainsaw’s starting procedure. It may take a few pulls to get the engine running, especially if the carburetor was severely clogged.

Tools Needed:

• Fuel container
• Screwdriver (for removing fuel filter if necessary)
• Fresh fuel
• Two-stroke oil
• Fuel stabilizer (optional)

My Experience: I once had a Poulan Pro chainsaw brought to me that hadn’t been started in over a year. The owner was convinced it needed a new carburetor. After a fresh fuel flush and a new spark plug, it fired right up!

Expert Fix #2: Cleaning the Carburetor Externally

If the fresh fuel flush doesn’t do the trick, the next step is to clean the carburetor externally. This involves spraying carburetor cleaner into the carburetor’s openings to dissolve any surface deposits.

Why it works: This method can dislodge loose debris and varnish without requiring a complete carburetor disassembly.

Step-by-Step Guide:

1. Locate the Carburetor: The carburetor is typically located behind the air filter. Remove the air filter cover and air filter.
2. Identify Carburetor Openings: Locate the carburetor’s air intake and the throttle valve. The throttle valve is the flap that opens and closes as you squeeze the throttle trigger.
3. Spray Carburetor Cleaner: With the engine off, spray carburetor cleaner liberally into the carburetor’s air intake and around the throttle valve. Move the throttle trigger to open and close the throttle valve, ensuring the cleaner reaches all areas.
4. Let it Soak: Allow the carburetor cleaner to soak for about 15-20 minutes. This gives the cleaner time to dissolve any deposits.
5. Attempt to Start: After soaking, attempt to start the chainsaw. It may take a few pulls to get it running. If it starts, let it idle for a few minutes to allow the carburetor cleaner to clear out any remaining debris.
6. Repeat if Necessary: If the chainsaw still runs poorly, repeat the cleaning process.

Tools Needed:

• Screwdriver (for removing air filter cover)
• Carburetor cleaner
• Safety glasses (to protect your eyes from carburetor cleaner)

Important Note: Carburetor cleaner is a powerful solvent. Work in a well-ventilated area and avoid getting it on your skin or in your eyes.

My Experience: I’ve found that this method is particularly effective for chainsaws that have been sitting idle for a few months. The deposits haven’t had time to harden completely, making them easier to dissolve with carburetor cleaner.

Expert Fix #3: Carburetor Adjustment

Sometimes, a carburetor issue isn’t due to a clog but rather an incorrect adjustment of the high-speed (H) and low-speed (L) screws.

Why it works: The H and L screws control the fuel-air mixture at different engine speeds. If these screws are not properly adjusted, the engine may run too lean (not enough fuel) or too rich (too much fuel), leading to poor performance or starting problems.

Step-by-Step Guide:

1. Locate the Adjustment Screws: The H and L adjustment screws are typically located on the side of the carburetor. They are usually labeled “H” for high-speed and “L” for low-speed. Some carburetors also have an “LA” screw for idle speed adjustment.
2. Find the Factory Settings: Consult your Poulan Pro chainsaw’s manual for the factory settings of the H and L screws. These settings are a starting point for adjustment. If you don’t have the manual, a general starting point is 1 to 1 1/2 turns out from fully closed (gently seated).
3. Adjust the Low-Speed (L) Screw: Start the chainsaw and let it warm up for a few minutes. Turn the L screw slowly clockwise (in) until the engine starts to bog down or stall. Then, turn the L screw slowly counterclockwise (out) until the engine starts to run rough. Find the sweet spot in between where the engine idles smoothly and responds quickly to the throttle.
4. Adjust the High-Speed (H) Screw: With the engine running at full throttle (carefully!), listen to the engine. If it sounds like it’s screaming or running lean (high-pitched), turn the H screw counterclockwise (out) to richen the mixture. If it sounds like it’s bogging down or running rich (low-pitched), turn the H screw clockwise (in) to lean the mixture. The goal is to find the setting where the engine runs smoothly at full throttle without screaming or bogging down. Important: Running the engine too lean at high speed can damage the engine.
5. Adjust the Idle Speed (LA) Screw (if applicable): If your carburetor has an LA screw, adjust it to set the idle speed to the manufacturer’s specification. The engine should idle smoothly without stalling.

Tools Needed:

• Screwdriver (usually a small flathead screwdriver)
• Tachometer (optional, but helpful for precise high-speed adjustment)
• Ear protection (when running the chainsaw at full throttle)

Important Note: Carburetor adjustment is a delicate process. Make small adjustments and listen carefully to the engine. If you’re not comfortable adjusting the carburetor yourself, it’s best to take it to a qualified technician.

My Experience: I’ve found that the H screw is often the culprit when a chainsaw starts easily but lacks power at high speed. A slight adjustment of the H screw can often restore full power. I always recommend using a tachometer to ensure the engine is running within the manufacturer’s specified RPM range at full throttle. This helps prevent engine damage.

Expert Fix #4: Carburetor Rebuild

If the previous fixes haven’t worked, it’s time to consider a carburetor rebuild. This involves disassembling the carburetor, cleaning all the components, and replacing any worn or damaged parts.

Why it works: A carburetor rebuild allows you to thoroughly clean all the tiny passages and jets within the carburetor, removing any stubborn deposits that may be causing problems. It also allows you to replace worn parts, such as the needle valve and diaphragm, which can affect carburetor performance.

Step-by-Step Guide:

1. Remove the Carburetor: Disconnect the fuel line and throttle linkage from the carburetor. Remove the bolts or screws that hold the carburetor to the engine. Carefully remove the carburetor.
2. Disassemble the Carburetor: Place the carburetor on a clean workbench. Carefully disassemble the carburetor, following the instructions in your Poulan Pro chainsaw’s manual or a carburetor rebuild kit. Pay close attention to the location of all the parts, as they need to be reassembled in the correct order. Take pictures as you disassemble it!
3. Clean the Carburetor Components: Clean all the carburetor components with carburetor cleaner. Use a small brush or pipe cleaner to clean the tiny passages and jets. Ensure that all the passages are clear and free of debris. I often use compressed air to blow out the passages after cleaning them with carburetor cleaner.
4. Inspect the Components: Inspect all the carburetor components for wear or damage. Pay particular attention to the needle valve, diaphragm, and gaskets. Replace any worn or damaged parts with new ones from a carburetor rebuild kit.
5. Reassemble the Carburetor: Reassemble the carburetor, following the instructions in your Poulan Pro chainsaw’s manual or a carburetor rebuild kit. Ensure that all the parts are properly seated and tightened.
6. Install the Carburetor: Reinstall the carburetor on the engine. Reconnect the fuel line and throttle linkage.
7. Adjust the Carburetor: Adjust the H and L screws to the factory settings.

Tools Needed:

• Screwdrivers (various sizes)
• Pliers
• Carburetor cleaner
• Carburetor rebuild kit
• Compressed air (optional)
• Clean workbench
• Safety glasses

Important Note: Carburetor rebuilds can be complex. If you’re not comfortable disassembling and reassembling the carburetor yourself, it’s best to take it to a qualified technician.

My Experience: I’ve rebuilt dozens of carburetors over the years. The key is to be patient, organized, and meticulous. Take your time, clean everything thoroughly, and follow the instructions carefully. A carburetor rebuild can often restore a chainsaw to like-new performance. A good rebuild kit will include a new diaphragm, which is critical for proper fuel metering. The old diaphragm often becomes stiff and brittle over time, leading to poor performance.

Expert Fix #5: Carburetor Replacement

If a carburetor rebuild doesn’t solve the problem, or if the carburetor is severely damaged, the best option may be to replace it with a new one.

Why it works: A new carburetor eliminates any potential issues with the old carburetor, ensuring that the engine receives the correct fuel-air mixture.

Step-by-Step Guide:

1. Identify the Correct Carburetor: Ensure that you purchase the correct carburetor for your Poulan Pro chainsaw model. Check the part number on the old carburetor or consult your chainsaw’s manual.
2. Remove the Old Carburetor: Disconnect the fuel line and throttle linkage from the old carburetor. Remove the bolts or screws that hold the carburetor to the engine. Carefully remove the old carburetor.
3. Install the New Carburetor: Install the new carburetor on the engine. Reconnect the fuel line and throttle linkage.
4. Adjust the Carburetor: Adjust the H and L screws to the factory settings.

Tools Needed:

• Screwdrivers (various sizes)
• Pliers
• New carburetor

Important Note: When purchasing a new carburetor, make sure to buy a high-quality carburetor from a reputable supplier. Cheap aftermarket carburetors may not perform as well as the original equipment carburetor.

My Experience: I’ve found that replacing a carburetor is often the most cost-effective solution when dealing with a severely damaged or corroded carburetor. The time and effort required to rebuild a heavily damaged carburetor may outweigh the cost of a new one. Plus, a new carburetor comes with a warranty, providing peace of mind.

Additional Tips and Considerations

• Spark Plug: Always check the spark plug when troubleshooting engine problems. A fouled or damaged spark plug can cause starting and running issues. Replace the spark plug if necessary.
• Air Filter: A dirty air filter restricts airflow to the engine, which can affect carburetor performance. Clean or replace the air filter regularly.
• Fuel Line: Inspect the fuel line for cracks or leaks. A cracked or leaking fuel line can cause fuel starvation. Replace the fuel line if necessary.
• Impulse Line: Many chainsaws use an impulse line to transfer crankcase pressure to the carburetor, assisting in fuel delivery. Check this line for cracks or leaks.
• Storage: When storing your Poulan Pro chainsaw for an extended period, drain the fuel tank and run the engine until it stalls to empty the carburetor. This will help prevent fuel deposits from forming in the carburetor. Alternatively, use a fuel stabilizer.
• Safety: Always wear safety glasses and gloves when working on your chainsaw. Disconnect the spark plug wire before working on the engine to prevent accidental starting.

Case Study: Reviving a Neglected Poulan Pro

I was called to help a friend who had a Poulan Pro chainsaw sitting unused in his shed for over two years. He’d tried starting it several times without success and was ready to give up on it.

Here’s what I did:

1. Initial Assessment: The chainsaw was visibly dirty, and the fuel tank contained old, gummy fuel.
2. Fresh Fuel Flush: I drained the old fuel and replaced it with a fresh mixture of gasoline and two-stroke oil, along with a fuel stabilizer. I also replaced the fuel filter, which was completely clogged.
3. External Carburetor Cleaning: I sprayed carburetor cleaner into the carburetor’s openings and let it soak for about 20 minutes.
4. Spark Plug Check: The spark plug was fouled, so I cleaned it with a wire brush.
5. Attempt to Start: After a few pulls, the chainsaw sputtered to life! However, it ran very rough and stalled frequently.
6. Carburetor Adjustment: I adjusted the H and L screws to fine-tune the fuel-air mixture. After some careful adjustments, the chainsaw idled smoothly and responded quickly to the throttle.
7. Test Cut: I made a few test cuts to ensure the chainsaw was running properly under load. It performed flawlessly!

The entire process took about an hour, and my friend was thrilled to have his chainsaw back in working order. This case study highlights the importance of starting with the simplest fixes and working your way up to more complex procedures.

Strategic Insights for Long-Term Maintenance

Beyond the immediate fixes, consider these strategic insights for maintaining your Poulan Pro chainsaw and preventing future carburetor problems:

• Regular Use: Use your chainsaw regularly to keep the fuel system flowing and prevent fuel deposits from forming.
• Proper Fuel Storage: Store fuel in a clean, airtight container and use a fuel stabilizer.
• Preventative Maintenance: Perform regular maintenance, such as cleaning the air filter, checking the spark plug, and inspecting the fuel line.
• Professional Service: If you’re not comfortable working on your chainsaw yourself, take it to a qualified technician for regular service.

Conclusion: Getting Back to Work

Troubleshooting and fixing a Poulan Pro chainsaw carburetor can seem daunting, but by following these expert fixes and understanding the underlying principles, you can often get your chainsaw back in action without resorting to expensive repairs. Remember to start with the simplest solutions, be patient, and work systematically. With a little effort, you can save money and keep your chainsaw running smoothly for years to come. Now, get out there and get that wood cut!

Learn more