Chainsaw Starts Then Dies Immediately (5 Expert Fixes For Stihl 046)

Okay, here we go. Let’s dive into this chainsaw conundrum!

It’s a crisp autumn morning, the kind that makes you want to be outdoors, working with wood. The air smells of pine and damp earth, a scent I’ve come to associate with productive days. I remember one particular day, several years back, when I was tackling a downed oak on my property. This oak was a beast, the kind that demands respect. I grabbed my trusty Stihl 046, a workhorse I’d relied on for years. I gave the cord a pull, and she roared to life… briefly. Then, silence. Chainsaw starts then dies immediately.

Frustration mounted as I repeated the process. Start, roar, die. Start, roar, die. It felt like the chainsaw was mocking me. This wasn’t just a minor inconvenience; it was a full-blown roadblock in my day’s plan. I knew I needed to figure it out quickly. After a bit of troubleshooting (and a lot of head-scratching), I managed to get it running. But that experience taught me a valuable lesson: understanding the common causes of this issue is crucial for any chainsaw user, especially those of us who rely on our saws for everything from firewood prep to serious logging work.

The user intent behind the query “Chainsaw Starts Then Dies Immediately (5 Expert Fixes for Stihl 046)” is clear: the user is experiencing a specific problem with their Stihl 046 chainsaw (or a similar model) and needs practical, actionable solutions to diagnose and fix the issue. They are likely seeking expert advice, not just general troubleshooting tips. They are looking for a targeted approach that addresses the common reasons why a chainsaw might start briefly and then stall.

So, let’s get down to brass tacks. Over the years, I’ve helped countless folks get their saws back up and running. Here are five expert fixes for a Stihl 046 (or similar chainsaw) that starts and then dies immediately, drawing from my experiences and deep knowledge of these machines.

Chainsaw Starts Then Dies Immediately: 5 Expert Fixes for Stihl 046

1. Fuel System Troubles: The Lifeblood of Your Chainsaw

The fuel system is the heart of your chainsaw. Without a properly functioning fuel system, your saw is as good as a paperweight. This is often the first place I look when a saw is giving me trouble.

Understanding the Fuel System

Before we dive into fixes, let’s understand the components:

Fuel Tank: Holds the fuel mixture (typically gasoline and 2-cycle oil).
Fuel Filter: Located inside the fuel tank, it prevents debris from entering the fuel line.
Fuel Line: Carries fuel from the tank to the carburetor.
Carburetor: Mixes fuel and air in the correct ratio for combustion.
Spark Plug: Ignites the fuel-air mixture in the cylinder.

Fix 1: Clogged Fuel Filter

A clogged fuel filter is one of the most common culprits. Over time, debris from the fuel tank can accumulate, restricting fuel flow.

Symptoms: Chainsaw starts briefly, then dies. May run poorly or not at all.
Diagnosis: Remove the fuel filter from the tank (usually accessible through the fuel cap opening). Inspect for debris. If it looks dirty, it’s time for a replacement.
Solution: Replace the fuel filter. These are inexpensive and readily available. I recommend keeping a few spares on hand.
Personal Tip: When replacing the filter, take a look inside the tank. If you see a lot of sediment, drain the tank completely and clean it out with fresh fuel.

Fix 2: Blocked Fuel Line

The fuel line can become brittle and cracked over time, leading to air leaks or blockages.

Symptoms: Similar to a clogged fuel filter – chainsaw starts briefly, then dies.
Diagnosis: Inspect the fuel line for cracks, kinks, or leaks. You can also try disconnecting the fuel line from the carburetor and blowing air through it to check for blockages.
Solution: Replace the fuel line. Again, this is a relatively inexpensive repair. Make sure you use a fuel line that is compatible with the fuel you are using (especially if you are using ethanol-blended fuel).
Data Point: Ethanol in fuel can degrade rubber and plastic fuel lines over time. Consider using fuel lines specifically designed for ethanol-blended fuels.

Fix 3: Carburetor Issues

The carburetor is a complex component that requires precise adjustments. A dirty or improperly adjusted carburetor can cause a variety of problems.

Symptoms: Chainsaw starts briefly, then dies. May also run rough, idle poorly, or lack power.
Diagnosis:
- Dirty Carburetor: Remove the air filter and inspect the carburetor throat. Look for dirt, varnish, or other deposits.
- Carburetor Adjustment: The carburetor has three main adjustment screws:
  - L (Low-Speed): Adjusts the fuel mixture at idle.
  - H (High-Speed): Adjusts the fuel mixture at high RPMs.
  - LA (Idle Speed): Adjusts the engine’s idle speed.
Solution:
- Cleaning the Carburetor: Use carburetor cleaner to thoroughly clean the carburetor. Pay close attention to the jets and passages. You may need to disassemble the carburetor for a more thorough cleaning.
- Carburetor Adjustment: This is where things get a bit tricky. The factory settings for the carburetor screws are a good starting point, but you may need to fine-tune them to get your saw running properly.
  - Start with the factory settings: Refer to your Stihl 046 owner’s manual for the recommended settings. Typically, this involves turning the L and H screws fully in (gently!) and then backing them out a specific number of turns.
  - Adjust the L screw: Start the chainsaw and let it warm up. Adjust the L screw until the engine idles smoothly without stalling.
  - Adjust the LA screw: Adjust the LA screw until the engine idles at the correct speed (again, refer to your owner’s manual for the recommended RPM).
  - Adjust the H screw: This is best done while the chainsaw is under load (e.g., cutting wood). Adjust the H screw until the engine runs smoothly at full throttle without bogging down or sputtering.
Caution: Be careful not to overtighten the carburetor screws, as this can damage them.
Personal Story: I once spent an entire afternoon trying to adjust a carburetor on an old McCulloch chainsaw. I was convinced I had it dialed in perfectly, but the saw still wouldn’t run right under load. Finally, I realized that the high-speed jet was partially blocked. A quick cleaning with a fine wire solved the problem.

2. Ignition System Issues: Sparking the Flame

The ignition system is responsible for creating the spark that ignites the fuel-air mixture in the cylinder. If the ignition system is faulty, the chainsaw may not start at all, or it may start briefly and then die.

Understanding the Ignition System

The main components of the ignition system are:

Spark Plug: Creates the spark that ignites the fuel-air mixture.
Ignition Coil: Generates the high voltage needed to create the spark.
Flywheel: Contains magnets that induce a current in the ignition coil.
Ignition Module: Controls the timing of the spark.

Fix 4: Faulty Spark Plug

A faulty spark plug is a common cause of ignition problems.

Symptoms: Chainsaw starts briefly, then dies. May also be difficult to start or run poorly.
Diagnosis:
- Visual Inspection: Remove the spark plug and inspect it. Look for cracks, carbon buildup, or other damage.
- Spark Test: Reconnect the spark plug to the spark plug wire and hold the metal part of the spark plug against the engine block. Pull the starter cord. You should see a strong, blue spark. If the spark is weak, yellow, or non-existent, the spark plug is likely faulty.
Solution: Replace the spark plug. Use the correct type of spark plug for your Stihl 046. Refer to your owner’s manual for the recommended spark plug.
Data Point: Spark plugs should be replaced periodically, typically every 50-100 hours of use.

Fix 5: Ignition Coil Problems

The ignition coil is responsible for generating the high voltage needed to create the spark. If the ignition coil is faulty, the chainsaw may not start at all, or it may start briefly and then die.

Symptoms: Chainsaw starts briefly, then dies. May also be difficult to start or not start at all.
Diagnosis:
- Spark Test (Again): If you’ve already tested the spark plug and found it to be good, the ignition coil is the next likely culprit.
- Resistance Test: Use a multimeter to measure the resistance of the ignition coil. Refer to your Stihl 046 service manual for the correct resistance values.
- Air Gap: Check the air gap between the ignition coil and the flywheel. This gap must be within the specified range for the ignition system to function properly. Refer to your service manual for the correct air gap.
Solution:
- Adjust Air Gap: If the air gap is incorrect, adjust it to the specified value.
- Replace Ignition Coil: If the ignition coil is faulty, it will need to be replaced. This is a more complex repair that may require specialized tools and knowledge.
Caution: When working with the ignition system, be careful not to touch the spark plug wire while the engine is running. This can result in a painful electric shock.

3. Air Intake Issues: Letting the Engine Breathe

The air intake system provides the engine with the air it needs for combustion. If the air intake system is blocked or restricted, the chainsaw may not start or run properly.

Understanding the Air Intake System

The main components of the air intake system are:

Air Filter: Prevents dirt and debris from entering the engine.
Air Filter Housing: Protects the air filter and directs airflow to the carburetor.
Intake Manifold: Connects the carburetor to the engine cylinder.

Air Filter Maintenance

A dirty air filter can restrict airflow to the engine, causing it to run poorly or not at all.

Symptoms: Chainsaw starts briefly, then dies. May also run rough, lack power, or be difficult to start.
Diagnosis: Remove the air filter and inspect it. If it is dirty, clean or replace it.
Solution:
- Cleaning the Air Filter: Most air filters can be cleaned with soap and water. Allow the filter to dry completely before reinstalling it.
- Replacing the Air Filter: If the air filter is damaged or excessively dirty, replace it with a new one.
Data Point: Clean your air filter regularly, typically every 5-10 hours of use, depending on the conditions.
Personal Tip: I often carry a spare air filter with me when I’m working in the woods. That way, I can quickly swap out a dirty filter without having to stop and clean it.

4. Exhaust System Problems: Clearing the Way

The exhaust system removes exhaust gases from the engine. If the exhaust system is blocked or restricted, the chainsaw may not start or run properly.

Understanding the Exhaust System

The main components of the exhaust system are:

Exhaust Port: The opening in the cylinder where exhaust gases exit the engine.
Muffler: Reduces noise and directs exhaust gases away from the operator.
Spark Arrestor: Prevents sparks from exiting the exhaust system and potentially starting a fire.

Exhaust Port and Muffler Inspection

A blocked exhaust port or muffler can restrict the flow of exhaust gases, causing the engine to overheat and run poorly.

Symptoms: Chainsaw starts briefly, then dies. May also run rough, lack power, or overheat.
Diagnosis:
- Visual Inspection: Inspect the exhaust port and muffler for carbon buildup or other obstructions.
- Muffler Removal: Remove the muffler and inspect the exhaust port.
Solution:
- Cleaning the Exhaust Port: Use a scraper or wire brush to remove carbon buildup from the exhaust port.
- Cleaning the Muffler: Clean the muffler with carburetor cleaner or a wire brush.
- Cleaning the Spark Arrestor: The spark arrestor is a small screen located inside the muffler. Clean it with a wire brush.
Caution: Be careful when working with the exhaust system, as it can be very hot.

5. Mechanical Issues: Digging Deeper

If you’ve checked all of the above and your chainsaw is still starting and then dying, there may be a more serious mechanical problem.

Compression Test

Low compression can prevent the engine from starting or running properly.

Symptoms: Chainsaw starts briefly, then dies. May also be difficult to start or lack power.
Diagnosis: Use a compression tester to measure the compression in the cylinder. Refer to your Stihl 046 service manual for the correct compression values.
Solution: If the compression is low, there may be a problem with the piston rings, cylinder, or valves. This is a more complex repair that may require specialized tools and knowledge.

Crankshaft Seals

Leaky crankshaft seals can cause air leaks, which can affect engine performance.

Symptoms: Chainsaw starts briefly, then dies. May also run rough, idle poorly, or be difficult to start.
Diagnosis: Inspect the crankshaft seals for leaks. You can also use a leak-down tester to check for air leaks in the engine.
Solution: If the crankshaft seals are leaking, they will need to be replaced. This is a more complex repair that may require specialized tools and knowledge.

Wood Anatomy and Properties: Understanding Your Material

Understanding the wood you’re cutting is fundamental to effective chainsaw use and firewood preparation. Different wood species have varying densities, moisture contents, and burning characteristics.

Hardwood vs. Softwood

Hardwoods: Generally denser and burn longer than softwoods. Examples include oak, maple, and ash. These are ideal for sustained heat in stoves or fireplaces.
Softwoods: Typically less dense and easier to ignite. Pine, fir, and spruce are common softwoods. They’re great for kindling or starting fires quickly, but don’t provide the long burn times of hardwoods.
Data Point: Oak can have a BTU (British Thermal Unit) rating of around 28 million per cord, while pine might be closer to 20 million BTU per cord. This difference significantly impacts heating efficiency.

Moisture Content Dynamics

Green Wood: Freshly cut wood has a high moisture content (often 50% or higher). Burning green wood results in low heat output, excessive smoke, and creosote buildup in chimneys.
Seasoned Wood: Wood that has been properly dried (seasoned) has a moisture content of 20% or less. Seasoned wood burns hotter, cleaner, and more efficiently.
Seasoning Techniques:
- Stacking: Stack wood in a single row, off the ground, with gaps between pieces for air circulation.
- Location: Choose a sunny, windy location for faster drying.
- Time: Allow wood to season for at least 6-12 months, depending on the species and climate.
Data Point: Properly seasoned wood can yield up to 50% more heat than green wood.

Logging Tool Selection and Maintenance Best Practices

Choosing the right logging tools and maintaining them properly is essential for safety and efficiency.

Chainsaw Selection

Size and Power: Select a chainsaw that is appropriate for the size of the trees you’ll be cutting. A Stihl 046 is a great all-around saw for felling medium to large trees.
Bar Length: Choose a bar length that is long enough to cut through the diameter of the trees you’ll be felling, but not so long that it becomes unwieldy.
Safety Features: Look for chainsaws with safety features such as a chain brake, throttle lock, and anti-vibration system.

Chainsaw Maintenance

Chain Sharpening: Keep your chainsaw chain sharp for efficient cutting and reduced kickback risk. Use a chainsaw file or a chain grinder to sharpen the chain regularly.
Chain Tension: Maintain proper chain tension to prevent the chain from derailing or binding.
Bar Lubrication: Use chainsaw bar oil to lubricate the chain and bar. This reduces friction and wear.
Air Filter Cleaning: Clean the air filter regularly to ensure proper airflow to the engine.
Spark Plug Replacement: Replace the spark plug periodically to ensure reliable ignition.

Other Essential Logging Tools

Felling Axe or Wedge: Used to help direct the fall of a tree.
Cant Hook or Peavey: Used to roll and position logs.
Measuring Tape: Used to measure log lengths.
Safety Gear: Always wear safety glasses, hearing protection, gloves, and sturdy boots when working with logging tools.

Firewood Seasoning Techniques and Safety Considerations

Proper firewood seasoning is crucial for efficient burning and reducing creosote buildup. Safety should always be a top priority.

Seasoning Techniques

Stacking Methods:
- Single Row: Allows for maximum air circulation.
- Circular Stacks: Can be aesthetically pleasing but may not dry as evenly.
- Elevated Stacks: Use pallets or skids to keep wood off the ground.
Covering Wood: Cover the top of the woodpile to protect it from rain and snow, but leave the sides open for ventilation.
Wood Species Considerations: Hardwoods generally take longer to season than softwoods.
Data Point: A moisture meter is a valuable tool for determining when firewood is properly seasoned. Aim for a moisture content of 20% or less.

Safety Considerations

Personal Protective Equipment (PPE): Always wear safety glasses, gloves, and sturdy boots when handling firewood.
Lifting Techniques: Lift with your legs, not your back. Avoid twisting while lifting.
Stacking Safety: Stack wood carefully to prevent it from collapsing.
Insect and Pest Control: Be aware of insects and pests that may be present in firewood. Store firewood away from your home to prevent infestations.
Fire Safety: Keep a fire extinguisher or water hose nearby when burning firewood.

Project Planning and Execution: From Forest to Fireplace

Effective project planning is key to a successful firewood preparation project.

Site Assessment

Tree Selection: Choose trees that are dead, dying, or diseased. Avoid cutting healthy trees unless necessary.
Felling Plan: Plan the felling direction carefully to avoid damaging property or injuring yourself.
Access and Transportation: Consider how you will access the trees and transport the logs to your processing area.

Processing and Splitting

Cutting Logs to Length: Cut logs to the desired length for your fireplace or wood stove.
Splitting Wood:
- Manual Splitting: Use a splitting axe or maul to split wood by hand.
- Hydraulic Splitter: A hydraulic splitter can make splitting wood much easier and faster, especially for large logs.
Stacking and Seasoning: Stack the split wood in a well-ventilated area to season.

Cost-Benefit Analysis

Equipment Costs: Consider the cost of chainsaws, splitting tools, and other equipment.
Fuel and Maintenance Costs: Factor in the cost of fuel, oil, and maintenance for your equipment.
Time Investment: Estimate the amount of time it will take you to complete the project.
Value of Firewood: Determine the value of the firewood you will produce.
Data Point: A hydraulic splitter can significantly reduce the time and effort required to split wood, but it also represents a significant upfront investment.

Case Study: Reviving a Neglected Stihl 046

I once acquired a Stihl 046 that had been sitting unused in a barn for years. It was in rough shape, but I saw potential. Here’s how I brought it back to life, addressing the “starts then dies” issue:

Fuel System Overhaul: The fuel tank was full of old, gummy fuel. I completely disassembled the fuel system, replacing the fuel filter, fuel line, and cleaning the carburetor. The carburetor was particularly gunked up, requiring a thorough soaking in carburetor cleaner.
Ignition System Check: The spark plug was fouled, so I replaced it. I also checked the ignition coil and found that the air gap was slightly off. I adjusted it to the correct specification.
Air Filter Replacement: The air filter was completely disintegrated. I replaced it with a new one.
Exhaust System Cleaning: The spark arrestor was clogged with carbon buildup. I cleaned it with a wire brush.
Mechanical Inspection: I performed a compression test and found that the compression was within the acceptable range. I also checked the crankshaft seals and found no signs of leaks.

After completing these steps, the Stihl 046 started right up and ran like a champ. This project reinforced the importance of a systematic approach to troubleshooting chainsaw problems.

Conclusion: Keeping Your Chainsaw Running Strong

The “chainsaw starts then dies immediately” problem can be frustrating, but it’s often caused by a few common issues. By systematically checking the fuel system, ignition system, air intake system, and exhaust system, you can usually diagnose and fix the problem yourself. And if all else fails, don’t hesitate to consult a qualified chainsaw mechanic.

Remember to prioritize safety when working with chainsaws and other logging tools. Always wear appropriate PPE and follow safe operating procedures. With proper maintenance and care, your chainsaw will provide you with years of reliable service.

Key Takeaways:

Fuel system issues (clogged filter, blocked line, dirty carburetor) are common causes.
A faulty spark plug or ignition coil can prevent the engine from running.
A dirty air filter or clogged exhaust system can restrict airflow.
Regular maintenance is essential for preventing problems.

Next Steps:

Start by checking the fuel filter and spark plug.
If those are okay, move on to the carburetor and ignition coil.
If you’re not comfortable working on your chainsaw yourself, take it to a qualified mechanic.

Now, get out there and get cutting! Just remember to stay safe and keep that chain sharp.