6 Most Common Stihl MS 391 Problems: Resolve with Expert Tips

The STIHL MS 391 chainsaw is a rugged and dependable tool, favored by both professional lumberjacks and homeowners for its exceptional performance and durability. However, like all machines, the STIHL MS 391 is not immune to common problems that can occasionally affect its functionality.

Brief Overview of the STIHL MS 391 Chainsaw

The STIHL MS 391 is a reliable and powerful chainsaw designed for both professional loggers and homeowners. With its robust build and impressive cutting capabilities, it’s no wonder that it’s a popular choice among those in need of a high-performance chainsaw.

Importance of Addressing Common Problems for Optimal Performance

However, like any piece of equipment, the STIHL MS 391 is not without its issues. These common problems can sometimes hinder its performance and, if left unattended, may even result in damage. This blog post aims to shed light on these problems and provide practical solutions to ensure your STIHL MS 391 runs at its best.

Purpose of the Blog Post

The primary purpose of this blog post is to equip STIHL MS 391 owners with the knowledge and expert tips needed to resolve six of the most common issues that may arise. By the end of this guide, you’ll have the tools and information necessary to diagnose and rectify problems related to starting, power, idling, chain oil systems, overheating, and maintenance. Let’s dive into these issues one by one, providing you with comprehensive guidance for maintaining and optimizing your STIHL MS 391 chainsaw.

Problem 1: Starting Issues

Starting your STIHL MS 391 chainsaw should be a straightforward process, but sometimes, it can be a bit tricky. Let’s dive into the common causes of starting issues, provide a step-by-step troubleshooting guide, and share expert tips to help you resolve these problems efficiently.

Causes of Starting Problems

Starting issues with your STIHL MS 391 can be frustrating, but understanding the potential causes is the first step in solving the problem. Here are some common reasons why your chainsaw might have difficulty starting:

  1. Fuel Issues: Check if the fuel mixture is correct. A faulty fuel mixture can lead to starting problems.
  2. Clogged Air Filter: A dirty or clogged air filter can restrict airflow, making it difficult for the engine to start.
  3. Ignition Problems: Faulty ignition components can prevent the spark plug from firing, causing the chainsaw to stall.
  4. Flooded Engine: Over-priming the engine can flood it with fuel, making it hard to start.
  5. Compression Issues: Low compression due to a worn-out piston or cylinder can make starting difficult.
  6. Cold Start: In extremely cold conditions, the engine might need a bit more warm-up time.

stihl ms 391 troubleshooting

Step-by-Step Troubleshooting Guide

Troubleshooting starting issues requires a systematic approach. Follow these steps to identify and fix the problem:

  1. Check Fuel and Fuel Mixture: Ensure that your fuel tank is filled with fresh, high-quality fuel and that the fuel mixture is correct according to the manufacturer’s recommendations.
  2. Inspect the Air Filter: Remove and inspect the air filter. If it’s dirty, clean or replace it. A clean air filter allows for proper airflow.
  3. Examine the Spark Plug: Inspect the spark plug for signs of wear or fouling. Replace it if necessary.
  4. Check the Ignition System: Ensure the ignition system components, including the ignition coil and wires, are in good condition. Faulty components can lead to a weak spark.
  5. Address a Flooded Engine: If you suspect a flooded engine, follow the manufacturer’s instructions for clearing a flooded engine.
  6. Warm Up the Engine: In cold weather, allow the engine to warm up for a few minutes before attempting to start it.

Expert Tips for Resolving Starting Problems

Here are some expert tips to help you resolve starting issues with your STIHL MS 391:

  • Regular Maintenance: Keep up with routine maintenance, including cleaning the air filter, checking the spark plug, and ensuring the fuel mixture is correct.
  • Use Quality Fuel: Always use high-quality fuel with the appropriate oil-to-gas ratio to prevent fuel-related starting problems.
  • Warm-Up: In colder temperatures, allow the chainsaw to warm up before engaging the throttle. This can make starting easier.
  • Seek Professional Help: If you’ve tried troubleshooting and starting problems persist, consider consulting a professional for a thorough inspection and repair.

By following these steps and expert tips, you can improve the starting reliability of your STIHL MS 391 chainsaw and get back to work with confidence.

Problem 2: Low Power or Poor Performance

A chainsaw like the STIHL MS 391 is known for its impressive power and performance, making it an ideal choice for various cutting tasks. However, if you’ve noticed a decline in power or a decrease in its overall performance, it’s essential to understand the reasons behind these issues and how to restore your chainsaw’s optimal capabilities.

Reasons behind Decreased Power and Performance

Several factors can contribute to reduced power and poor performance in your STIHL MS 391 chainsaw:

  1. Fuel Quality: The quality of the fuel you’re using can greatly affect your chainsaw’s performance. Old or low-quality fuel can lead to decreased power output.
  2. Air Filter Issues: A clogged or dirty air filter restricts airflow to the engine, resulting in reduced power and performance.
  3. Spark Plug Problems: A fouled or worn-out spark plug can lead to incomplete combustion, causing power loss.
  4. Carbon Buildup: Carbon deposits on the piston or exhaust port can reduce power output.
  5. Clogged Exhaust System: A clogged or damaged exhaust system can inhibit proper exhaust flow, affecting performance.
  6. Low Compression: Reduced compression due to worn-out piston rings or cylinder walls can lead to decreased power.

Diagnostic Checklist for Identifying Issues

To identify the specific issues causing low power and poor performance in your STIHL MS 391, follow this diagnostic checklist:

  1. Check Fuel Quality: Ensure you’re using fresh, high-quality fuel with the correct oil-to-gas ratio.
  2. Inspect the Air Filter: Remove and inspect the air filter. Clean or replace it if it’s dirty.
  3. Examine the Spark Plug: Inspect the spark plug for wear and fouling. Replace it if needed.
  4. Clean Carbon Deposits: If you suspect carbon buildup, consider cleaning the piston and exhaust port.
  5. Check the Exhaust System: Ensure the exhaust system is not clogged or damaged.
  6. Test Compression: A compression test can help identify low compression issues. If it’s low, consider a professional inspection.

Expert Recommendations for Restoring Power and Performance

Here are expert recommendations to restore the power and performance of your STIHL MS 391 chainsaw:

  • Use High-Quality Fuel: Always use fresh, high-quality fuel with the appropriate oil-to-gas ratio.
  • Regular Air Filter Maintenance: Clean or replace the air filter regularly to maintain proper airflow.
  • Spark Plug Replacement: Change the spark plug at regular intervals, as recommended in the user manual.
  • Carbon Buildup Maintenance: Periodically inspect and clean the piston and exhaust port to prevent carbon buildup.
  • Exhaust System Inspection: Check the exhaust system for clogs or damage and address any issues promptly.
  • Professional Help: If power and performance problems persist, consider consulting a professional for a comprehensive inspection and necessary repairs.

By following these expert recommendations and using the diagnostic checklist, you can address low power and poor performance issues in your STIHL MS 391 chainsaw effectively, ensuring it continues to deliver the performance you rely on for your cutting tasks.

Problem 3: Chainsaw Not Idling Properly

When your trusty STIHL MS 391 chainsaw doesn’t idle as it should, it can disrupt your workflow and lead to a host of other problems. In this section, we’ll explore the common causes of improper idling, provide a step-by-step guide to diagnose idling issues and offer expert advice to help you correct these problems.

Common Causes of Improper Idling

Improper idling in your STIHL MS 391 can be attributed to several factors. Understanding these causes is crucial to addressing the issue effectively:

  1. Dirty or Clogged Air Filter: An air filter clogged with dirt and debris restricts the airflow, affecting the engine’s idle speed.
  2. Carburetor Problems: A malfunctioning carburetor can disrupt the air-fuel mixture, leading to idling problems.
  3. Idle Adjustment Screw: An improperly adjusted idle screw can cause the engine to idle too high or too low.
  4. Fuel Issues: Poor-quality or old fuel can lead to idling problems as it affects the combustion process.
  5. Vacuum Leaks: Leaks in the intake system can disrupt the engine’s ability to maintain a steady idle.

How to Diagnose Idling Issues

Diagnosing idling issues in your STIHL MS 391 requires a systematic approach. Here’s a step-by-step guide to help you pinpoint the problem:

  1. Inspect the Air Filter: Remove and inspect the air filter. If it’s dirty, clean or replace it.
  2. Check the Carburetor: Ensure the carburetor is functioning correctly. Clean or rebuild it if necessary.
  3. Idle Adjustment: Verify the idle adjustment screw is set to the manufacturer’s specifications. Make necessary adjustments if it’s off.
  4. Fuel Quality: Use fresh, high-quality fuel with the correct oil-to-gas ratio.
  5. Vacuum Leaks: Inspect the intake system for leaks and address any issues found.

Expert Advice for Correcting Idling Problems

To correct idling problems with your STIHL MS 391 chainsaw, follow these expert recommendations:

  • Regular Air Filter Maintenance: Clean or replace the air filter regularly to ensure proper airflow.
  • Carburetor Maintenance: Periodically clean or rebuild the carburetor to maintain the correct air-fuel mixture.
  • Idle Adjustment: Set the idle adjustment screw to the manufacturer’s specifications for the correct idle speed.
  • Use High-Quality Fuel: Always use fresh, high-quality fuel with the appropriate oil-to-gas ratio.
  • Vacuum Leak Inspection: Routinely check for vacuum leaks and fix any issues to maintain a steady idle.

By applying these expert recommendations and systematically diagnosing idling issues, you can ensure that your STIHL MS 391 chainsaw idles properly, allowing you to work more efficiently and preventing further problems down the line.

Problem 4: Chain Oil System Malfunctions

A smoothly operating chain oil system is essential for keeping your STIHL MS 391 chainsaw in top condition. In this section, we’ll provide an overview of chain oil system problems, a step-by-step guide to diagnose oil system issues, and expert tips to help you fix any malfunctions you might encounter.

Overview of Chain Oil System Problems

The chain oil system is responsible for ensuring that the chainsaw’s chain remains properly lubricated during operation. When the chain oil system malfunctions, it can lead to a range of issues, including:

  1. Insufficient Lubrication: A failing oil system may not provide enough lubrication, leading to chain and bar wear.
  2. Oil Leaks: Leaks in the oil system can result in oil wastage and a messy work environment.
  3. Clogging: Clogs in the oil lines or oil pump can disrupt the flow of oil to the chain and bar.
  4. Premature Chain and Bar Wear: Insufficient oiling can lead to faster wear on the chain and bar, reducing their lifespan.

Step-by-Step Guide to Diagnose Oil System Issues

Diagnosing problems with the chain oil system of your STIHL MS 391 chainsaw requires a systematic approach. Here’s a step-by-step guide to help you identify issues:

  1. Inspect Chain Lubrication: Start by checking if the chain is being adequately lubricated during operation. Insufficient lubrication indicates a problem with the oil system.
  2. Look for Oil Leaks: Examine the chainsaw for any visible oil leaks, paying close attention to the oil tank and oil lines.
  3. Clean the Oil Ports: If the chain isn’t receiving enough oil, clean the oil ports on the bar and the oiler holes on the chainsaw body.
  4. Check the Oil Filter: Inspect and clean the oil filter to ensure it’s not clogged.
  5. Verify Oil Pump Operation: Run the chainsaw while holding it over a clean piece of cardboard. If oil isn’t dispensed onto the cardboard, the oil pump may be faulty.

Expert Tips for Fixing Chain Oil System Malfunctions

To address chain oil system malfunctions in your STIHL MS 391 chainsaw, follow these expert tips:

  • Clean Regularly: Clean the oil ports, bar, and oil filter regularly to prevent clogs and ensure proper lubrication.
  • Use Quality Bar and Chain Oil: Always use high-quality bar and chain oil designed for chainsaws.
  • Inspect for Leaks: Routinely check for oil leaks and address any leaks promptly to prevent oil wastage.
  • Check Oil Pump: If the oil pump is not working correctly, consider consulting a professional for repair or replacement.

By following these expert tips and systematically diagnosing oil system issues, you can ensure that your STIHL MS 391 chainsaw operates with proper lubrication, extending the lifespan of your chain and bar and maintaining the efficiency of your cutting tasks.

Problem 5: Chainsaw Overheating

Overheating in your STIHL MS 391 chainsaw can lead to serious issues, including damage to vital components. In this section, we’ll explore the reasons for overheating, how to identify overheating problems and provide expert guidance on preventing and addressing this concern.

Reasons for Overheating in STIHL MS 391

Several factors can contribute to the overheating of your STIHL MS 391 chainsaw:

  1. Incorrect Fuel Mixture: The wrong fuel-to-oil ratio can lead to incomplete combustion, generating excess heat.
  2. Airflow Blockages: Clogged air filters or obstructions in the cooling fins can hinder proper airflow, causing overheating.
  3. Dirty Cylinder Fins: Accumulated dirt and debris on the cylinder fins can impede heat dissipation.
  4. Continuous Operation: Prolonged use without adequate breaks for cooling can cause the engine to overheat.
  5. Improper Maintenance: Neglecting regular maintenance can lead to the buildup of heat-inducing deposits.

How to Identify Overheating Problems

To identify overheating problems in your STIHL MS 391 chainsaw, watch out for these signs:

  1. Excessive Heat: The chainsaw becomes extremely hot to the touch during operation.
  2. Reduced Power: Overheating can lead to a decrease in power output and performance.
  3. Engine Stalling: The engine may stall or shut down unexpectedly due to overheating.
  4. Unusual Noises: Unusual knocking or pinging noises from the engine can indicate overheating.

Expert Guidance on Preventing and Addressing Overheating

To prevent and address overheating in your STIHL MS 391 chainsaw, consider the following expert guidance:

  • Correct Fuel Mixture: Always use the manufacturer-recommended fuel-to-oil ratio for the chainsaw.
  • Regular Air Filter Maintenance: Clean or replace the air filter regularly to ensure proper airflow for cooling.
  • Clean Cylinder Fins: Keep the cylinder fins clean from dirt and debris to enable effective heat dissipation.
  • Take Breaks: Avoid continuous operation, and take breaks to allow the chainsaw to cool down.
  • Routine Maintenance: Adhere to a regular maintenance schedule, cleaning the spark arrestor, muffler, and other components to prevent overheating.
  • Professional Inspection: If overheating problems persist, consider consulting a professional for a thorough inspection to identify and address any underlying issues.

Problem 6: Maintenance and Care Neglect

Maintenance and care are the lifeblood of your STIHL MS 391 chainsaw. Neglecting these crucial aspects can lead to a host of problems and even permanent damage. In this section, we’ll emphasize the importance of regular maintenance, highlight common mistakes in maintenance, and offer expert advice on proper care and maintenance practices.

The Importance of Regular Maintenance

Regular maintenance is the key to keeping your STIHL MS 391 chainsaw in optimal working condition. Here’s why it’s essential:

  1. Prolong Lifespan: Regular maintenance can significantly extend the lifespan of your chainsaw, saving you money on replacements.
  2. Optimal Performance: Properly maintained chainsaws run efficiently, delivering the power and performance you depend on.
  3. Safety: Maintained chainsaws are safer to use, reducing the risk of accidents caused by malfunctions.
  4. Resale Value: If you ever plan to sell or trade-in your chainsaw, well-maintained equipment holds its value.

Common Mistakes in Maintenance

Several common mistakes in maintenance can compromise the performance and longevity of your STIHL MS 391:

  1. Irregular Cleaning: Neglecting to clean the air filter, cylinder fins, and other components can hinder proper airflow and heat dissipation.
  2. Inadequate Lubrication: Failing to lubricate the chain and bar properly can lead to increased wear and potential damage.
  3. Incorrect Fuel Mixture: Using the wrong fuel-to-oil ratio can cause engine problems and overheating.
  4. Ignoring the Spark Plug: Overlooking the spark plug can lead to starting and performance issues.
  5. Neglecting Chain Tension: An improperly tensioned chain can be dangerous and cause damage to the chainsaw.

Expert Advice on Proper Care and Maintenance Practices

To ensure your STIHL MS 391 chainsaw receives the care and maintenance it deserves, follow this expert advice:

  • Regular Cleaning: Clean the air filter, cylinder fins, and other components regularly to prevent clogs and overheating.
  • Proper Lubrication: Lubricate the chain and bar according to the manufacturer’s recommendations to reduce wear and friction.
  • Fuel Quality: Always use fresh, high-quality fuel with the correct oil-to-gas ratio for your chainsaw.
  • Spark Plug Maintenance: Inspect and clean or replace the spark plug as recommended in the user manual.
  • Chain Tension: Keep the chain properly tensioned to ensure safe and efficient operation.
  • Scheduled Maintenance: Adhere to a maintenance schedule outlined in the user manual, including filter replacement and general checks.

common Stihl ms 391 issues

Additional Resources

When it comes to maintaining and troubleshooting your STIHL MS 391 chainsaw, it’s essential to have access to the right resources. In this section, we’ll provide you with a list of valuable additional resources that can assist you in addressing common problems and keeping your chainsaw in top-notch condition.

Provide Links to STIHL’s Official Resources

  • STIHL USA Official Website: The official website of STIHL USA is a comprehensive resource for product information, user manuals, safety guidelines, and more. You can find detailed information specific to your STIHL MS 391 chainsaw.
  • STIHL Product Manuals: The product manuals section on STIHL’s website offers access to user manuals for various STIHL products, including the STIHL MS 391. These manuals contain essential information on maintenance, operation, and troubleshooting.

Suggest Relevant User Manuals and Guides

  • STIHL MS 391 Owner’s Manual: The official owner’s manual provided by STIHL offers detailed guidance on using and maintaining your STIHL MS 391 chainsaw. It’s an invaluable resource for understanding the proper care and operation of your equipment.
  • Chainsaw Maintenance Guide: STIHL’s chainsaw maintenance guide provides step-by-step instructions for keeping your chainsaw in top condition, which can help prevent common problems from occurring.

Recommend Online Forums and Communities for Further Assistance

  • ArboristSite.com: ArboristSite is a popular online community where professionals and enthusiasts discuss all things related to chainsaws, including the STIHL MS 391. You can ask questions, share experiences, and seek advice from a knowledgeable community.
  • Forestry.com Forums: The Forestry.com forums cover a wide range of forestry and chainsaw topics, making it a valuable resource for troubleshooting and maintenance discussions related to your chainsaw.
  • STIHL Chainsaw Owners Forum: This forum is dedicated to STIHL chainsaw owners and is an excellent place to connect with fellow STIHL MS 391 users. You can find valuable insights and solutions to common problems.

These additional resources, including official sources, user manuals, and online forums, are invaluable in helping you resolve common problems and maintain your STIHL MS 391 chainsaw effectively. They offer a wealth of information and a community of experts and enthusiasts who can assist you in keeping your chainsaw in prime working condition.

Conclusion

As we conclude our exploration of the six most common problems that STIHL MS 391 chainsaw owners may encounter, let’s recap the key takeaways, emphasize the importance of timely resolutions, and encourage users to prioritize proper maintenance to prevent future issues.

Recap of the 6 Common STIHL MS 391 Problems

Throughout this blog post, we’ve delved into the following common problems associated with the STIHL MS 391 chainsaw:

  1. Starting Issues: We’ve covered the causes of starting problems and provided a troubleshooting guide to help you get your chainsaw up and running efficiently.
  2. Low Power or Poor Performance: We discussed the reasons behind decreased power and performance and offered expert tips for restoring your chainsaw’s capabilities.
  3. Chainsaw Not Idling Properly: We explained the common causes of improper idling, how to diagnose idling problems, and provided expert advice for correcting these issues.
  4. Chain Oil System Malfunctions: An overview of chain oil system problems, a step-by-step diagnostic guide, and expert tips for fixing malfunctions were detailed.
  5. Chainsaw Overheating: We outlined the reasons for overheating, how to identify overheating problems, and provided expert guidance on preventing and addressing overheating concerns.
  6. Maintenance and Care Neglect: The importance of regular maintenance, common mistakes to avoid, and expert advice on proper care and maintenance practices were highlighted.

Emphasize the Significance of Timely Resolutions

Addressing these problems promptly is crucial for the continued performance and longevity of your STIHL MS 391 chainsaw. Timely resolutions not only save you time and money but also ensure safe and efficient operation. Neglecting these issues can lead to more severe damage and costly repairs down the line.

Encourage Users to Seek Professional Assistance if Needed

While this blog post offers expert tips and guidance for resolving common problems, it’s important to recognize that some issues may require professional attention. If you’ve followed the troubleshooting steps and the problem persists or if you’re uncertain about any aspect of your chainsaw’s maintenance, don’t hesitate to seek the expertise of a certified STIHL technician. Their experience and knowledge can help diagnose and address issues accurately.

The Importance of Proper Maintenance for Preventing Future Issues

In conclusion, we cannot stress enough the significance of regular maintenance and proper care. Regularly scheduled maintenance not only prevents common problems but also ensures your chainsaw operates at its peak performance. By following manufacturer-recommended maintenance practices and keeping an eye on your equipment, you can enjoy the reliability and efficiency of your STIHL MS 391 chainsaw for years to come.

Thank you for joining us in this comprehensive exploration of common STIHL MS 391 problems and their resolutions. We hope this guide empowers you to keep your chainsaw in optimal working condition, allowing you to tackle your cutting tasks with confidence and ease.

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