Stihl Chainsaw Cold Start Issues (Expert Tips To Fix MS 290)

Is your Stihl MS 290 refusing to roar to life on a cold morning? Trust me, I know the frustration. There’s nothing worse than being ready to tackle a pile of logs only to be defeated by a stubborn chainsaw. Over my years of cutting wood, I’ve wrestled with countless starting issues. From flooded engines in the dead of winter to vapor lock in the summer heat, I’ve pretty much seen it all. The good news is that most cold start problems with the Stihl MS 290 are easily fixable with a bit of know-how and some basic troubleshooting.

In this guide, I’m going to share my expert tips for diagnosing and resolving those frustrating cold start issues. We’ll cover everything from fuel delivery and ignition problems to carburetor adjustments and maintenance best practices. I’ll walk you through each step in detail, providing clear instructions and practical advice to get your MS 290 running smoothly again.

Diagnosing Cold Start Problems on Your Stihl MS 290

Before you start tearing things apart, it’s essential to properly diagnose the problem. A systematic approach will save you time and prevent unnecessary repairs.

Checking the Basics: Fuel, Spark, and Compression

These are the three fundamental elements required for any internal combustion engine to run. Let’s start with the easiest checks first.

Fuel: Is there fuel in the tank? Sounds obvious, but it happens! Is the fuel fresh? Old, stale fuel can cause starting problems. I recommend using fuel that is no more than 30 days old, especially if it contains ethanol. Ethanol attracts moisture, which can lead to corrosion and fuel system issues. I always use a fuel stabilizer like STA-BIL to extend the life of my fuel.
Spark: Remove the spark plug and inspect it. Is it wet with fuel? If so, the engine might be flooded. Is the electrode clean and dry? A fouled spark plug can prevent the engine from starting. Clean the plug with a wire brush or replace it with a new one. To test for spark, reattach the spark plug to the spark plug wire and ground the plug against the engine block. Pull the starter cord and look for a strong blue spark. A weak or non-existent spark indicates a problem with the ignition system.
Compression: While less common, low compression can also cause starting problems. You can check compression using a compression tester. Insert the tester into the spark plug hole and pull the starter cord several times. A healthy MS 290 should have a compression reading of at least 120 PSI. If the compression is significantly lower, it could indicate worn piston rings, a damaged cylinder, or a leaking valve.

Understanding the Choke and Starting Procedure

The choke restricts airflow to the carburetor, creating a richer fuel mixture that is easier to ignite in a cold engine. Knowing how to use the choke properly is crucial for starting your MS 290.

Cold Start Procedure: Engage the chain brake. Move the master control lever to the choke position (usually fully extended). Pull the starter cord until the engine attempts to start or “pops.” This usually takes 3-5 pulls. Once the engine pops, move the master control lever to the half-choke position (usually one notch in). Pull the starter cord again until the engine starts and runs smoothly. Allow the engine to warm up for a few seconds before disengaging the chain brake and using the saw.
Troubleshooting Choke Issues: If the engine floods easily, you may be using too much choke. Try starting the saw with the master control lever in the half-choke position instead. If the engine doesn’t start at all, the choke may not be working properly. Check the choke linkage to make sure it is moving freely and that the choke plate is closing completely.

Common Culprits: Fuel System Problems

The fuel system is often the source of cold start issues. Let’s examine the most common problems.

Clogged Fuel Filter: The fuel filter prevents dirt and debris from entering the carburetor. A clogged fuel filter restricts fuel flow, making it difficult to start the engine. To check the fuel filter, remove it from the fuel tank and inspect it. If it’s dirty or clogged, replace it with a new one. I recommend replacing the fuel filter annually as part of your regular maintenance routine. A new fuel filter for an MS 290 typically costs around $5-$10.
Dirty Carburetor: The carburetor mixes fuel and air in the correct proportions for combustion. Over time, the carburetor can become clogged with varnish and deposits, especially if you use fuel that contains ethanol. A dirty carburetor can cause a variety of problems, including hard starting, poor performance, and stalling. To clean the carburetor, you’ll need to disassemble it and soak the parts in carburetor cleaner. Use compressed air to blow out any remaining debris. Be sure to follow the manufacturer’s instructions when reassembling the carburetor. If you’re not comfortable cleaning the carburetor yourself, you can take it to a qualified repair shop. A carburetor rebuild kit for an MS 290 typically costs around $20-$30.
Fuel Line Leaks: Fuel lines can crack and leak over time, causing a loss of fuel pressure and making it difficult to start the engine. Inspect the fuel lines for cracks, leaks, or damage. Replace any damaged fuel lines with new ones. Make sure to use fuel line that is compatible with gasoline and oil.

My Experience: I once spent an entire morning trying to start my MS 290, only to discover that a tiny crack in the fuel line was causing a significant fuel leak. Replacing the fuel line took just a few minutes, and the saw started right up.

Investigating Ignition System Faults

If you’ve ruled out fuel problems, the next step is to investigate the ignition system.

Faulty Spark Plug: As mentioned earlier, a fouled or damaged spark plug can prevent the engine from starting. Replace the spark plug with a new one. Make sure to use the correct spark plug for your MS 290. The recommended spark plug is a Bosch WSR 6 F or an NGK BPMR 7 A. The gap should be 0.5 mm (0.020 in).
Weak Ignition Coil: The ignition coil generates the high-voltage spark that ignites the fuel mixture. A weak ignition coil can produce a weak spark, making it difficult to start the engine, especially in cold weather. You can test the ignition coil using a multimeter. Check the primary and secondary resistance. The primary resistance should be between 0.2 and 0.6 ohms, and the secondary resistance should be between 2,000 and 4,000 ohms. If the resistance is outside of these ranges, replace the ignition coil. Replacing the ignition coil is more involved and requires removing the flywheel.
Damaged Flywheel Key: The flywheel key aligns the flywheel with the crankshaft. If the flywheel key is damaged, the timing will be off, preventing the engine from starting. Inspect the flywheel key for damage. If it’s damaged, replace it with a new one. Replacing the flywheel key requires removing the flywheel.

Key Takeaway: A systematic approach to diagnosing cold start problems will save you time and money. Start with the basics (fuel, spark, compression) and then move on to more complex components like the carburetor and ignition system.

Step-by-Step Guide to Fixing Common Cold Start Issues

Now that we’ve covered the basics of diagnosing cold start problems, let’s move on to the specific steps you can take to fix them.

Cleaning or Replacing the Spark Plug

This is often the first and easiest step in troubleshooting cold start issues.

Remove the spark plug: Use a spark plug wrench to remove the spark plug from the cylinder head.
Inspect the spark plug: Look for signs of fouling, such as carbon buildup, oil, or fuel. Also, check for cracks or damage to the insulator.
Clean the spark plug: If the spark plug is only slightly fouled, you can try cleaning it with a wire brush or spark plug cleaner. Be careful not to damage the electrode.
Gap the spark plug: Use a spark plug gapping tool to set the gap to the manufacturer’s specifications (0.5 mm or 0.020 in for the MS 290).
Install the spark plug: Reinstall the spark plug and tighten it to the correct torque (15-20 Nm or 11-15 ft-lbs).

If the spark plug is heavily fouled or damaged, replace it with a new one.

Cleaning the Carburetor

A dirty carburetor is a common cause of cold start problems.

Remove the air filter: Remove the air filter cover and the air filter.
Remove the carburetor: Disconnect the fuel lines and throttle linkage from the carburetor. Remove the carburetor from the engine.
Disassemble the carburetor: Carefully disassemble the carburetor, taking note of the location of each part. It’s helpful to take pictures as you go.
Clean the carburetor parts: Soak the carburetor parts in carburetor cleaner for at least 30 minutes. Use a small brush to scrub away any stubborn deposits.
Rinse and dry the parts: Rinse the carburetor parts with clean water and dry them with compressed air.
Reassemble the carburetor: Reassemble the carburetor, making sure to install all of the parts in the correct location.
Install the carburetor: Reinstall the carburetor on the engine. Connect the fuel lines and throttle linkage.
Adjust the carburetor: Adjust the carburetor according to the manufacturer’s specifications.

Carburetor Adjustment: The MS 290 carburetor has three adjustment screws:

L (Low-speed): Adjusts the fuel mixture at idle and low speeds.
H (High-speed): Adjusts the fuel mixture at high speeds.
LA (Idle speed): Adjusts the engine idle speed.

To adjust the carburetor, start by turning both the L and H screws clockwise until they are lightly seated. Then, turn them counterclockwise 1 turn each. Start the engine and let it warm up. Adjust the LA screw until the engine idles smoothly without stalling. Fine-tune the L and H screws to achieve the best performance. The engine should accelerate smoothly without hesitation.

Caution: Over-tightening the L and H screws can damage the carburetor.

Replacing the Fuel Filter and Fuel Lines

A clogged fuel filter or leaking fuel lines can restrict fuel flow and cause starting problems.

Remove the fuel filter: Use a fuel line pick or pliers to remove the fuel filter from the fuel tank.
Install the new fuel filter: Attach the new fuel filter to the fuel line and insert it into the fuel tank.
Inspect the fuel lines: Inspect the fuel lines for cracks, leaks, or damage.
Replace the fuel lines: If the fuel lines are damaged, replace them with new ones. Make sure to use fuel line that is compatible with gasoline and oil.
Secure the fuel lines: Secure the fuel lines with fuel line clamps.

I recommend replacing the fuel filter annually and the fuel lines every 2-3 years, or sooner if they show signs of damage.

Checking and Adjusting the Ignition System

If you suspect a problem with the ignition system, you’ll need to perform some additional tests.

Test the spark: Remove the spark plug and attach it to the spark plug wire. Ground the spark plug against the engine block. Pull the starter cord and look for a strong blue spark. If the spark is weak or non-existent, there may be a problem with the ignition coil or the flywheel.
Test the ignition coil: Use a multimeter to test the primary and secondary resistance of the ignition coil. If the resistance is outside of the specified range, replace the ignition coil.
Inspect the flywheel key: Remove the flywheel and inspect the flywheel key for damage. If the flywheel key is damaged, replace it with a new one.
Adjust the air gap: The air gap between the ignition coil and the flywheel should be 0.2-0.4 mm (0.008-0.016 in). Use a feeler gauge to adjust the air gap.

Note: Working on the ignition system can be dangerous. If you’re not comfortable performing these tests, take your saw to a qualified repair shop.

My Experience: I once had a persistent cold start problem with my MS 290 that I couldn’t figure out. I replaced the spark plug, cleaned the carburetor, and replaced the fuel filter, but the saw still wouldn’t start reliably. Finally, I decided to check the air gap between the ignition coil and the flywheel. I discovered that the air gap was way too large. After adjusting the air gap to the correct specification, the saw started on the first pull.

Key Takeaway: Don’t overlook the ignition system when troubleshooting cold start problems. A weak spark or incorrect air gap can prevent the engine from starting.

Advanced Troubleshooting Techniques

If you’ve tried all of the basic troubleshooting steps and your MS 290 still won’t start, you may need to use some more advanced techniques.

Performing a Compression Test

Low compression can make it difficult to start the engine, especially in cold weather.

Remove the spark plug: Remove the spark plug from the cylinder head.
Install the compression tester: Install the compression tester into the spark plug hole.
Pull the starter cord: Pull the starter cord several times until the pressure gauge stops rising.
Read the compression: Read the compression on the pressure gauge. A healthy MS 290 should have a compression reading of at least 120 PSI.

If the compression is significantly lower than 120 PSI, there may be a problem with the piston rings, cylinder, or valves. In this case, you’ll need to take your saw to a qualified repair shop for further diagnosis and repair.

Checking for Air Leaks

Air leaks can cause a lean fuel mixture, which can make it difficult to start the engine.

Inspect the intake manifold: Inspect the intake manifold for cracks or leaks.
Inspect the carburetor mounting flange: Inspect the carburetor mounting flange for cracks or leaks.
Inspect the crankshaft seals: Inspect the crankshaft seals for leaks.

To check for air leaks, you can use a spray bottle filled with soapy water. Spray the soapy water around the intake manifold, carburetor mounting flange, and crankshaft seals. If you see bubbles forming, there is an air leak.

To fix an air leak, you’ll need to replace the affected parts.

Diagnosing Fuel Pump Issues

The fuel pump is responsible for delivering fuel from the fuel tank to the carburetor. If the fuel pump is not working properly, it can cause starting problems.

Check the fuel pump diaphragm: Remove the fuel pump cover and inspect the fuel pump diaphragm for cracks or damage.
Check the fuel pump check valves: Inspect the fuel pump check valves for clogs or damage.

If the fuel pump diaphragm or check valves are damaged, replace the fuel pump.

Key Takeaway: Advanced troubleshooting techniques like compression testing, checking for air leaks, and diagnosing fuel pump issues can help you identify and resolve more complex cold start problems.

Preventative Maintenance for Reliable Starts

The best way to avoid cold start problems is to perform regular preventative maintenance on your MS 290.

Regular Cleaning and Inspection

Clean the air filter: Clean the air filter after each use. A dirty air filter restricts airflow and can cause starting problems.
Clean the spark plug: Clean the spark plug every 25 hours of use.
Inspect the fuel lines: Inspect the fuel lines for cracks or leaks every 25 hours of use.
Inspect the chain: Inspect the chain for sharpness and damage before each use. A dull or damaged chain can put extra strain on the engine and make it harder to start.

Proper Fuel Storage and Handling

Use fresh fuel: Use fresh fuel that is no more than 30 days old.
Use a fuel stabilizer: Use a fuel stabilizer to extend the life of your fuel.
Store fuel properly: Store fuel in a cool, dry place away from direct sunlight.
Drain the fuel tank: Drain the fuel tank before storing the saw for extended periods.

Seasonal Maintenance Tasks

Spring: Check and replace the spark plug, fuel filter, and air filter. Clean the carburetor.
Fall: Drain the fuel tank and prepare the saw for winter storage.

My Routine: I make it a habit to clean my MS 290 after every use. I remove the air filter and clean it with soap and water. I also wipe down the entire saw with a clean cloth. This helps to prevent dirt and debris from accumulating and causing problems.

Sharpening and Maintaining the Chain

A sharp chain not only cuts more efficiently but also reduces the strain on the engine, making it easier to start and run smoothly.

Sharpen the chain regularly: Use a chainsaw file to sharpen the chain regularly.
Maintain the correct chain tension: Maintain the correct chain tension to prevent the chain from binding or derailing.
Lubricate the chain: Lubricate the chain with chainsaw bar and chain oil.

Remember: A well-maintained chain is a safe chain.

Key Takeaway: Preventative maintenance is the key to keeping your MS 290 running smoothly and reliably. Regular cleaning, proper fuel storage, and seasonal maintenance tasks will help you avoid cold start problems and extend the life of your saw.

Common Mistakes to Avoid

Even experienced chainsaw users can make mistakes that lead to cold start problems. Here are some common mistakes to avoid:

Over-Choking the Engine

Over-choking the engine can flood it with fuel, making it difficult to start. Avoid over-choking the engine by following the correct starting procedure. If the engine floods, remove the spark plug and pull the starter cord several times to clear the excess fuel.

Using Old or Stale Fuel

Old or stale fuel can cause a variety of problems, including hard starting, poor performance, and stalling. Always use fresh fuel that is no more than 30 days old.

Neglecting Air Filter Maintenance

A dirty air filter restricts airflow and can cause starting problems. Clean the air filter after each use.

Ignoring Fuel Line Cracks and Leaks

Fuel line cracks and leaks can cause a loss of fuel pressure and make it difficult to start the engine. Inspect the fuel lines for cracks, leaks, or damage regularly.

Forgetting Seasonal Storage Procedures

Failing to properly prepare your saw for seasonal storage can lead to corrosion and other problems. Drain the fuel tank and follow the manufacturer’s instructions for winter storage.

My Biggest Blunder: I once forgot to drain the fuel tank of my MS 290 before storing it for the winter. When I tried to start it in the spring, the carburetor was completely clogged with varnish. It took me hours to clean the carburetor and get the saw running again. I learned my lesson the hard way!

Key Takeaway: Avoid these common mistakes to prevent cold start problems and keep your MS 290 running smoothly.

When to Call a Professional

While many cold start problems can be fixed with some basic troubleshooting and maintenance, there are times when it’s best to call a professional.

Complex Engine Repairs

If you suspect a problem with the engine’s internal components, such as the piston rings, cylinder, or valves, it’s best to take your saw to a qualified repair shop. These repairs require specialized tools and knowledge.

Ignition System Issues

Diagnosing and repairing ignition system problems can be complex and dangerous. If you’re not comfortable working on the ignition system, take your saw to a professional.

Carburetor Rebuilds

Rebuilding a carburetor can be a delicate and time-consuming process. If you’re not experienced with carburetor repairs, it’s best to leave it to a professional.

Recurring Problems

If you’ve tried all of the troubleshooting steps and your MS 290 still won’t start reliably, there may be an underlying problem that requires professional diagnosis.

Remember: A qualified repair shop has the tools, knowledge, and experience to diagnose and repair even the most complex chainsaw problems.

Key Takeaway: Don’t hesitate to call a professional when you’re facing a problem that’s beyond your skill level or when you’re dealing with recurring issues.

Staying Safe While Troubleshooting

Safety should always be your top priority when working on your chainsaw.

Wear Protective Gear

Wear safety glasses, gloves, and hearing protection when working on your chainsaw.

Disconnect the Spark Plug Wire

Disconnect the spark plug wire before performing any maintenance or repairs. This will prevent the engine from accidentally starting.

Work in a Well-Ventilated Area

Work in a well-ventilated area when working with fuel or carburetor cleaner.

Use the Right Tools

Use the right tools for the job. Using the wrong tools can damage your chainsaw or cause injury.

Follow the Manufacturer’s Instructions

Always follow the manufacturer’s instructions when performing maintenance or repairs.

My Safety Rule: I always double-check to make sure the spark plug wire is disconnected before I start working on my chainsaw. It’s a simple step that can prevent a serious accident.

Key Takeaway: Safety should always be your top priority when working on your chainsaw. Wear protective gear, disconnect the spark plug wire, and follow the manufacturer’s instructions.

Conclusion: Mastering the Cold Start

Conquering cold start issues on your Stihl MS 290 is achievable with a blend of understanding, methodical troubleshooting, and consistent maintenance. I’ve shared my experiences, insights, and step-by-step guidance, equipping you with the knowledge to diagnose and resolve common problems.

Remember, a well-maintained chainsaw is a reliable chainsaw. By following the preventative maintenance tips and avoiding common mistakes, you can keep your MS 290 running smoothly for years to come. And when faced with a problem that’s beyond your expertise, don’t hesitate to seek the help of a qualified professional.