Chainsaw Starts Then Dies When You Give It Gas (Carburetor Fix Tips)

Cleaning a chainsaw carburetor can seem like a daunting task, but with a little patience and the right approach, it’s something most folks can tackle themselves. It’s not always a walk in the park, but it’s definitely more manageable than you might think.

Chainsaw Starts Then Dies When You Give It Gas: Carburetor Fix Tips

Have you ever been in the middle of bucking up some prime oak, ready to fill your wood shed before the winter chill sets in, only to have your chainsaw sputter, start, and then die the moment you give it some gas? It’s a common problem, and more often than not, the culprit is a dirty or improperly adjusted carburetor. Trust me, I’ve been there more times than I care to admit. It’s frustrating, especially when you’re on a tight schedule and relying on that saw to get the job done.

Globally, the firewood and wood processing industries are experiencing a fascinating shift. While large-scale logging continues to be a significant player, there’s a growing trend towards smaller, independent operations and hobbyists taking on wood processing tasks themselves. According to a recent report by the Food and Agriculture Organization (FAO), the demand for fuelwood remains strong, particularly in developing nations, while in developed countries, there’s a resurgence of interest in wood heating for its sustainability and cost-effectiveness. This means more people than ever are relying on chainsaws and need to understand how to keep them running smoothly.

This guide is designed to help you diagnose and fix a chainsaw that starts but dies when you give it gas, focusing primarily on carburetor issues. I’ll break down the process into easy-to-follow steps, share some of my personal experiences, and provide tips to help you avoid common pitfalls.

Understanding the Carburetor: The Heart of Your Chainsaw

Before we dive into the fix, let’s talk about what a carburetor actually does. Think of it as the heart of your chainsaw, responsible for mixing fuel and air in the correct ratio to create a combustible mixture that powers the engine. A carburetor’s job is to atomize the fuel into a fine mist and mix it with air. This mixture then enters the combustion chamber, where it’s ignited by the spark plug.

When the carburetor is dirty or improperly adjusted, the fuel-air mixture is thrown off, leading to a variety of problems, including the dreaded “starts then dies” scenario.

Why is My Chainsaw Doing This? (Common Causes)

There are several reasons why your chainsaw might be starting but then dying when you give it gas. Here are the most common:

• Dirty Carburetor: This is the most frequent offender. Over time, fuel can leave behind deposits, clogging the tiny passages within the carburetor. This restricts fuel flow, especially when the engine demands more fuel under load (when you give it gas).
• Incorrect Carburetor Adjustment: Carburetors have adjustment screws (usually labeled L, H, and sometimes T) that control the fuel-air mixture. If these screws are not properly adjusted, the engine will either run too lean (not enough fuel) or too rich (too much fuel), causing it to stall.
• Fuel Line Issues: Cracked or damaged fuel lines can allow air to enter the fuel system, disrupting the fuel flow to the carburetor.
• Fuel Filter Problems: A clogged fuel filter restricts fuel flow, starving the engine of fuel when it needs it most.
• Spark Plug Issues: While less common in this specific scenario, a fouled or damaged spark plug can contribute to poor engine performance.
• Air Filter Issues: A dirty air filter can restrict airflow into the carburetor, resulting in an overly rich fuel mixture.

Tools and Materials You’ll Need

Before you start tinkering, gather these essential tools and materials:

• Screwdrivers: A set of both flathead and Phillips head screwdrivers, in various sizes.
• Carburetor Cleaner: This is specifically designed to dissolve fuel deposits and varnish.
• Compressed Air: For blowing out passages in the carburetor. A can of compressed air will work, but an air compressor is ideal.
• Small Brushes: A set of small brushes, like carburetor cleaning brushes or even pipe cleaners, for scrubbing away debris.
• Needle-Nose Pliers: For removing small parts and fuel lines.
• Carburetor Adjustment Tool (Optional): Some chainsaws use proprietary carburetor adjustment tools. Check your chainsaw’s manual to see if you need one.
• New Fuel Filter: It’s good practice to replace the fuel filter whenever you’re working on the fuel system.
• New Spark Plug (Optional): If your spark plug is old or fouled, consider replacing it.
• Clean Rags: For wiping up spills and cleaning parts.
• Safety Glasses: Protect your eyes from flying debris and chemicals.
• Gloves: Protect your hands from fuel and chemicals.
• Chainsaw Manual: Your chainsaw’s manual is a valuable resource for specific information about your model.

Step-by-Step Carburetor Cleaning and Adjustment Guide

Okay, let’s get down to business. Here’s a detailed, step-by-step guide to cleaning and adjusting your chainsaw’s carburetor. Remember to work in a well-ventilated area, as gasoline fumes can be harmful.

Step 1: Safety First – Disconnect the Spark Plug

Before you do anything else, disconnect the spark plug wire. This prevents the chainsaw from accidentally starting while you’re working on it. Just pull the wire off the spark plug.

Step 2: Accessing the Carburetor

The location of the carburetor varies depending on the chainsaw model, but it’s usually located behind the air filter and near the engine. You’ll likely need to remove the air filter cover and the air filter itself to gain access.

Step 3: Removing the Air Filter

Remove the air filter. Inspect it for dirt and debris. If it’s dirty, clean it with soap and water, or replace it if it’s excessively dirty or damaged. A clean air filter is crucial for proper engine performance.

Step 4: Detaching the Fuel Lines and Throttle Linkage

Carefully detach the fuel lines from the carburetor. Use needle-nose pliers if necessary. Be prepared for some fuel to spill, so have a rag handy. Note the position of each fuel line so you can reattach them correctly later.

Next, detach the throttle linkage from the carburetor. This is usually a small rod or cable that connects the throttle trigger to the carburetor.

Step 5: Removing the Carburetor

Now you can remove the carburetor from the chainsaw. It’s usually held in place by a few screws or bolts. Once you’ve removed the fasteners, carefully pull the carburetor away from the engine.

Step 6: Disassembling the Carburetor

This is where things get a bit more intricate. Before you start disassembling the carburetor, take pictures of each step with your phone. This will be invaluable when it comes time to reassemble it.

1. Remove the Fuel Bowl: The fuel bowl is the small reservoir at the bottom of the carburetor. It’s usually held in place by a screw or bolt. Remove the screw and carefully remove the fuel bowl. Be careful, as there may be some fuel remaining in the bowl.
2. Remove the Float and Needle Valve: The float is a small, usually plastic, component that floats in the fuel bowl and controls the flow of fuel into the carburetor. The needle valve is a small, pointed valve that sits in the float and regulates the fuel flow. Carefully remove the float and needle valve.
3. Remove the Jets: The jets are small, brass fittings that control the amount of fuel that flows through the carburetor. There are usually two or three jets, labeled L (low speed), H (high speed), and sometimes I (idle). Use a small screwdriver to carefully remove the jets.
4. Inspect all parts: Once you’ve disassembled the carburetor, inspect all the parts for wear or damage. Pay close attention to the diaphragms, which are thin rubber membranes that can crack or become brittle over time.

Step 7: Cleaning the Carburetor

Now for the fun part – cleaning!

1. Spray with Carburetor Cleaner: Thoroughly spray all the carburetor parts with carburetor cleaner. Pay special attention to the jets and the small passages within the carburetor body.
2. Scrub with Small Brushes: Use small brushes to scrub away any stubborn deposits. Make sure to clean the inside of the jets and the passages in the carburetor body.
3. Blow Out with Compressed Air: Use compressed air to blow out all the passages in the carburetor body and the jets. This will remove any remaining debris.
4. Soak if Necessary: If the carburetor is particularly dirty, you can soak the parts in carburetor cleaner for a few hours.

Step 8: Reassembling the Carburetor

Now it’s time to put everything back together. Use the pictures you took earlier as a guide.

1. Reinstall the Jets: Carefully reinstall the jets, making sure they are tightened securely.
2. Reinstall the Float and Needle Valve: Reinstall the float and needle valve. Make sure the float moves freely and the needle valve seats properly.
3. Reinstall the Fuel Bowl: Reinstall the fuel bowl, making sure the gasket is in good condition.
4. Double-Check Everything: Before you move on, double-check that everything is properly installed and tightened.

Step 9: Reinstalling the Carburetor

Reinstall the carburetor onto the chainsaw. Reattach the fuel lines and throttle linkage, making sure they are securely connected. Refer to your photos to ensure proper placement.

Step 10: Adjusting the Carburetor

This is a crucial step. Improperly adjusted carburetors are a major cause of chainsaw problems.

1. Locate the Adjustment Screws: Locate the L (low speed), H (high speed), and T (idle) adjustment screws. These are usually located on the side of the carburetor.
2. Initial Settings: As a starting point, gently turn each screw clockwise until it is lightly seated. Then, back each screw out the following amounts:
   • L screw: 1 to 1 1/2 turns
   • H screw: 1 to 1 1/2 turns
   • T screw: Adjust this later, after the engine is running.
3. Starting the Chainsaw: Start the chainsaw. Let it warm up for a few minutes.
4. Adjusting the Low-Speed (L) Screw: Turn the L screw in or out until the engine idles smoothly without stalling. If the engine stalls, turn the screw out slightly. If the engine runs too fast, turn the screw in slightly.
5. Adjusting the High-Speed (H) Screw: This is a more critical adjustment. The H screw controls the fuel-air mixture at high engine speeds. To adjust it properly, you’ll need to listen to the engine. With the engine running at full throttle (safely!), turn the H screw in or out until the engine runs smoothly without bogging down or sputtering. Important: Running the engine too lean (turning the H screw in too far) can damage the engine. If you’re unsure, it’s better to err on the side of being slightly rich (turning the H screw out slightly).
6. Adjusting the Idle (T) Screw: The T screw controls the engine’s idle speed. Adjust this screw until the chain does not move at idle.
7. Fine-Tuning: After making these adjustments, let the engine run for a few minutes and then make any necessary fine-tuning adjustments. The goal is to have the engine idle smoothly, accelerate quickly, and run smoothly at full throttle without bogging down or sputtering.

Step 11: Reinstalling the Air Filter and Cover

Reinstall the air filter and the air filter cover.

Step 12: Testing the Chainsaw

Now it’s time to test your work. Start the chainsaw and let it warm up for a few minutes. Then, give it some gas and see if it runs smoothly. If it still stalls, you may need to repeat the carburetor cleaning and adjustment process.

Troubleshooting Tips

Even with a thorough cleaning and adjustment, you might still encounter problems. Here are some troubleshooting tips:

• Chainsaw Still Stalls: If the chainsaw still stalls when you give it gas, double-check the fuel lines and fuel filter. A cracked fuel line or a clogged fuel filter can restrict fuel flow.
• Engine Runs Rough: If the engine runs rough, try adjusting the carburetor screws slightly. A small adjustment can often make a big difference.
• Chainsaw Won’t Start: If the chainsaw won’t start at all, check the spark plug. A fouled or damaged spark plug can prevent the engine from starting.
• Carburetor Leaks Fuel: If the carburetor leaks fuel, the float or needle valve may be damaged or improperly seated. You may need to replace these parts.

Preventing Future Problems

Prevention is always better than cure. Here are some tips to help prevent future carburetor problems:

• Use Fresh Fuel: Old fuel can leave behind deposits that clog the carburetor. Always use fresh fuel, and add a fuel stabilizer to the fuel if you’re not going to use it within a few weeks.
• Clean the Air Filter Regularly: A dirty air filter can restrict airflow, causing the engine to run rich and deposit fuel in the carburetor. Clean the air filter regularly.
• Run the Chainsaw Regularly: Letting the chainsaw sit for extended periods can cause fuel to evaporate and leave behind deposits. Run the chainsaw regularly, even if you don’t need to use it, to keep the fuel flowing.
• Store the Chainsaw Properly: When storing the chainsaw for an extended period, drain the fuel tank and run the engine until it stalls to remove any remaining fuel from the carburetor.

Personal Story: The Case of the Stubborn Stihl

I remember one time I was helping a friend clear some land for a new barn. We had a mountain of oak and maple to tackle. His trusty Stihl chainsaw, usually a reliable workhorse, started acting up. It would start fine, but the moment you gave it gas, it would sputter and die. We were scratching our heads, thinking it might be something serious.

After checking the usual suspects – fuel lines, spark plug, air filter – I decided to take a closer look at the carburetor. It turned out to be absolutely gunked up with old fuel residue. It looked like someone had poured molasses into it! After a thorough cleaning and a careful adjustment, the Stihl roared back to life. It was a good reminder that even the best equipment needs regular maintenance.

Understanding Wood Properties and Tool Selection

While we’re talking chainsaws, it’s worth touching on the importance of understanding wood properties and selecting the right tools for the job. Different types of wood have different densities, hardness, and moisture content, which can affect how easily they are cut and split.

• Hardwoods vs. Softwoods: Hardwoods, like oak and maple, are denser and harder than softwoods, like pine and fir. This means they require more power to cut and split.
• Green Wood vs. Seasoned Wood: Green wood (freshly cut wood) has a high moisture content, making it heavier and harder to split. Seasoned wood (wood that has been allowed to dry) is lighter and easier to split.
• Chainsaws vs. Axes: Chainsaws are ideal for felling trees and bucking logs into shorter lengths. Axes are better suited for splitting logs, especially larger ones.

For example, oak, with its high density and interlocking grain, can be a real bear to split with an axe, especially when it’s green. A hydraulic log splitter is often the best tool for the job. On the other hand, pine, with its straight grain and lower density, can be easily split with an axe, even when it’s green.

Data and Statistics: Firewood Seasoning

Seasoning firewood is crucial for efficient burning and reducing creosote buildup in your chimney. Creosote is a flammable byproduct of burning wood that can cause chimney fires.

Here are some data points to keep in mind:

• Target Moisture Content: The ideal moisture content for firewood is between 15% and 20%.
• Drying Time: The amount of time it takes to season firewood depends on the type of wood, the climate, and how the wood is stacked. Generally, hardwoods take longer to season than softwoods. In a dry climate, firewood can be seasoned in as little as six months. In a humid climate, it can take a year or more.
• Stacking Method: Stacking firewood properly is essential for efficient drying. The wood should be stacked in rows, with space between the rows to allow for air circulation. The top of the stack should be covered to protect the wood from rain and snow.

A study by the University of Maine found that properly seasoned firewood burns 25% more efficiently than green wood. This means you’ll use less wood to heat your home, saving you money and reducing your carbon footprint.

Case Study: Firewood Preparation in the Appalachian Mountains

I once spent a summer working with a small firewood producer in the Appalachian Mountains. They had a well-oiled operation, processing hundreds of cords of firewood each year. Their secret? A combination of experience, hard work, and smart techniques.

They used a combination of chainsaws and hydraulic log splitters to process the wood. They stacked the firewood in long rows, with plenty of space between the rows for air circulation. They covered the top of the stacks with tarps to protect the wood from rain and snow. And they used a moisture meter to check the moisture content of the wood before selling it.

Their success was a testament to the importance of proper wood processing and seasoning techniques. They were able to produce high-quality firewood that burned efficiently and cleanly, earning them a loyal customer base.

Costs, Budgeting, and Resource Management

Wood processing and firewood preparation can be surprisingly expensive, especially if you’re starting from scratch. Here are some costs to consider:

• Chainsaw: A good quality chainsaw can cost anywhere from $300 to $1000 or more.
• Axes and Log Splitters: Axes can range from $50 to $200. Hydraulic log splitters can cost from $1000 to $5000 or more.
• Safety Gear: Safety glasses, gloves, and hearing protection are essential and can cost around $50 to $100.
• Fuel and Oil: Fuel and oil can add up quickly, especially if you’re processing a lot of wood.
• Maintenance and Repairs: Chainsaws and log splitters require regular maintenance and repairs.
• Storage: You’ll need a place to store your firewood, such as a woodshed or a covered area.

To save money, consider buying used equipment, borrowing tools from friends or neighbors, or renting equipment from a rental center. Also, be sure to shop around for the best prices on fuel, oil, and other supplies.

Next Steps and Additional Resources

If you’ve followed these steps and your chainsaw is still giving you trouble, you may need to take it to a qualified repair shop. A professional technician can diagnose and repair more complex problems.

Here are some additional resources that you may find helpful:

• Chainsaw Manufacturers: Stihl, Husqvarna, Echo
• Logging Tool Suppliers: Bailey’s, Forestry Suppliers
• Firewood Drying Equipment Rental Services: Check your local rental centers.
• Local Arborists and Tree Services: They may offer wood processing services or have surplus firewood for sale.

By understanding the principles of chainsaw operation and maintenance, you can keep your chainsaw running smoothly and safely for years to come. Happy cutting!

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