Stihl MS170 How to Start: Fix No-Start Issues Quickly (Pro Tips)

Imagine the crisp air of a fall morning, the satisfying scent of freshly cut wood, and the warmth of a crackling fire – all powered by your reliable Stihl MS170 chainsaw. But what happens when that trusty saw refuses to roar to life? Don’t let a stubborn engine ruin your day. I’m here to guide you through the ins and outs of starting your Stihl MS170, and more importantly, how to quickly diagnose and fix those frustrating no-start issues. This isn’t just another manual; it’s a culmination of years of experience, practical tips, and insider knowledge gleaned from countless hours in the woods.

The State of Wood: A Global Perspective

Before we dive into the mechanics, let’s take a moment to appreciate the bigger picture. The global demand for wood, whether for construction, furniture, or firewood, is constantly evolving. According to recent reports, the firewood market alone is projected to reach billions of dollars in the coming years, driven by both traditional heating needs and the growing popularity of wood-burning stoves and outdoor fireplaces. However, this demand also puts pressure on sustainable forestry practices and efficient wood processing. As a responsible woodworker or homeowner, understanding the lifecycle of wood, from forest to fire, is crucial.

In many regions, firewood remains a primary heating source. In Eastern Europe, for example, firewood accounts for a significant portion of household energy consumption, particularly in rural areas. Similarly, in parts of North America and Scandinavia, wood-burning stoves are experiencing a resurgence as homeowners seek alternative heating solutions and embrace a more sustainable lifestyle.

Understanding Your Stihl MS170: A Reliable Workhorse

The Stihl MS170 is a popular choice for homeowners and occasional users for a reason. It’s lightweight, easy to handle, and powerful enough for a variety of tasks, from pruning branches to cutting firewood. However, like any machine, it requires proper maintenance and understanding to perform optimally.

Mastering the Start: A Step-by-Step Guide

Starting a chainsaw might seem simple, but mastering the technique is key to ensuring a quick and reliable start, every time.

Step 1: Safety First!

• Personal Protective Equipment (PPE): Always wear appropriate PPE, including safety glasses, hearing protection, gloves, and sturdy boots.
• Clearance: Ensure you have a clear and stable work area, free from obstructions.
• Fuel Check: Make sure you’re using the correct fuel mixture (typically 50:1 unleaded gasoline to 2-stroke oil) and that the fuel tank is adequately filled.
• Chain Brake: Engage the chain brake. This is a crucial safety precaution to prevent accidental chain movement during starting.

Step 2: Priming the Engine

• Primer Bulb: Locate the primer bulb (a small, clear bubble usually near the carburetor). Press it firmly several times (typically 5-8 times) until you see fuel flowing through it. This primes the carburetor, ensuring that fuel is readily available for the initial combustion.
  • Pro Tip: Don’t over-prime! Flooding the engine is a common cause of starting problems.

Step 3: Setting the Choke

• Choke Lever: The choke lever controls the amount of air entering the carburetor. For a cold start, fully close the choke (move the lever to the “full choke” position). This enriches the fuel mixture, making it easier to start the engine when it’s cold.
  • Note: Some models may have a “half choke” position. Refer to your owner’s manual for specific instructions.

Step 4: Starting the Engine

• Placement: Place the chainsaw on a firm, flat surface. Hold it securely with one hand on the front handle and your foot firmly planted on the rear handle.
• Pull Starting: Grasp the starter handle firmly and pull it out slowly until you feel resistance. Then, give it a sharp, full pull. Repeat this several times until the engine sputters or attempts to start.
  • Technique is Key: Avoid pulling the cord out to its full extent, as this can damage the starter mechanism.
  • Listen Carefully: Pay attention to the engine sounds. A sputtering sound indicates that the engine is trying to start.

Step 5: Adjusting the Choke

• Warm-Up: Once the engine sputters or attempts to start, move the choke lever to the “half choke” or “run” position (depending on your model). This allows more air into the carburetor, leaning out the fuel mixture.
• Continued Pulling: Continue pulling the starter cord until the engine starts and runs smoothly.

Step 6: Disengaging the Chain Brake

• After Start: Once the engine is running smoothly, disengage the chain brake by pushing the lever forward.
• Idle Check: Let the chainsaw idle for a few moments to warm up before using it.

Troubleshooting No-Start Issues: A Pro’s Guide

Even with the best technique, sometimes your Stihl MS170 might refuse to start. Don’t despair! Here’s a systematic approach to diagnosing and fixing common no-start issues.

1. Fuel System Problems

• Fuel Quality: Stale or contaminated fuel is a leading cause of starting problems. Always use fresh fuel and the correct oil mixture.
  • Action: Drain the fuel tank and replace it with fresh fuel.
  • Pro Tip: Use a fuel stabilizer, especially if you’re storing the chainsaw for an extended period.
• Fuel Filter: A clogged fuel filter can restrict fuel flow to the carburetor.
  • Inspection: Locate the fuel filter inside the fuel tank (it’s usually attached to the fuel line). Remove it and inspect it for debris.
  • Action: Replace the fuel filter if it’s dirty or clogged.
  • Cost: Fuel filters are relatively inexpensive, typically costing between $5 and $10.
• Fuel Lines: Cracked or damaged fuel lines can leak air, preventing the engine from drawing fuel.
  • Inspection: Carefully inspect the fuel lines for cracks, leaks, or damage.
  • Action: Replace any damaged fuel lines.
  • Pro Tip: Use fuel line pliers to avoid damaging the fuel lines during removal and installation.
• Carburetor: The carburetor mixes fuel and air in the correct proportions for combustion. A dirty or clogged carburetor can cause starting problems.
  • Symptoms: Difficulty starting, rough idling, stalling.
  • Action: Clean the carburetor. You can use carburetor cleaner spray or disassemble it for a more thorough cleaning.
    • Caution: Carburetor cleaning can be complex. If you’re not comfortable with it, consider taking your chainsaw to a qualified technician.
  • Carburetor Adjustment: The carburetor has adjustment screws (usually labeled “H” for high speed and “L” for low speed) that control the fuel-air mixture. Incorrectly adjusted carburetors can cause starting and performance issues.
    • Action: Consult your owner’s manual for the proper carburetor adjustment procedure.
    • Pro Tip: Start by turning both screws all the way in (gently!) and then back them out the recommended number of turns.

2. Ignition System Problems

• Spark Plug: The spark plug ignites the fuel-air mixture in the cylinder. A fouled or worn spark plug can prevent the engine from starting.
  • Inspection: Remove the spark plug and inspect it for fouling (carbon buildup), damage, or excessive wear.
  • Action: Clean the spark plug with a wire brush or replace it with a new one.
  • Spark Plug Gap: Ensure that the spark plug gap is correct. Consult your owner’s manual for the proper gap specification.
    • Tool: Use a spark plug gap tool to adjust the gap.
  • Spark Test: To test if the spark plug is producing a spark, reattach the spark plug to the ignition lead, ground the spark plug against the engine block, and pull the starter cord. You should see a strong, blue spark.
    • Caution: Do not touch the spark plug while pulling the starter cord, as you could get an electric shock.
• Ignition Coil: The ignition coil provides the high voltage needed to create a spark. A faulty ignition coil can prevent the engine from starting.
  • Testing: Testing the ignition coil requires a multimeter and some technical knowledge. If you suspect a faulty ignition coil, it’s best to take your chainsaw to a qualified technician.
• Flywheel Key: The flywheel key aligns the flywheel with the crankshaft. If the flywheel key is sheared, the timing will be off, preventing the engine from starting.
  • Inspection: Remove the flywheel cover and inspect the flywheel key.
  • Action: Replace the flywheel key if it’s sheared.

3. Compression Problems

• Compression: The engine needs adequate compression to ignite the fuel-air mixture. Low compression can prevent the engine from starting.
  • Testing: Testing compression requires a compression tester. If you suspect low compression, it’s best to take your chainsaw to a qualified technician.
  • Possible Causes: Worn piston rings, damaged cylinder, leaking valves.

4. Exhaust System Problems

• Spark Arrestor: The spark arrestor prevents sparks from escaping the exhaust. A clogged spark arrestor can restrict exhaust flow, causing starting and performance problems.
  • Inspection: Remove the spark arrestor and inspect it for carbon buildup.
  • Action: Clean the spark arrestor with a wire brush or replace it.
• Exhaust Port: A blocked exhaust port can also restrict exhaust flow.
  • Inspection: Inspect the exhaust port for carbon buildup.
  • Action: Clean the exhaust port.

5. Other Potential Issues

• Air Filter: A dirty air filter can restrict airflow to the carburetor, causing starting and performance problems.
  • Inspection: Remove the air filter and inspect it for dirt and debris.
  • Action: Clean the air filter with compressed air or replace it with a new one.
• Choke Mechanism: Make sure the choke lever is functioning properly and that the choke plate is closing fully when the choke is engaged.
• Kill Switch: Ensure that the kill switch is in the “run” position. A faulty kill switch can prevent the engine from starting.

Real-World Examples and Case Studies

Let me share a couple of stories from my own experience that highlight the importance of proper diagnosis and maintenance.

• The Case of the Stale Fuel: I once spent an entire afternoon trying to start a Stihl MS170 that had been sitting in my shed for several months. I checked the spark plug, cleaned the air filter, and even tinkered with the carburetor, all to no avail. Finally, I realized that the fuel was stale. After draining the tank and replacing it with fresh fuel, the chainsaw started on the first pull! This taught me the valuable lesson of always using fresh fuel and a fuel stabilizer.
• The Case of the Clogged Spark Arrestor: A friend of mine was complaining that his chainsaw was losing power and stalling frequently. I suspected a clogged spark arrestor. After removing and cleaning the spark arrestor, the chainsaw ran like new again! This simple fix saved him a trip to the repair shop and a potentially costly repair bill.

Data-Backed Insights: Firewood Preparation for Optimal Drying

Now, let’s shift gears and talk about firewood preparation. Proper seasoning (drying) of firewood is crucial for efficient burning and maximizing heat output. Green wood (freshly cut wood) contains a high moisture content, typically ranging from 50% to 100% (or even higher for some species). Seasoned firewood, on the other hand, should have a moisture content of 20% or less.

• Moisture Content and Heat Output: Wood with a moisture content of 50% or higher will produce significantly less heat than seasoned wood. Much of the energy from combustion is used to evaporate the water in the wood, rather than producing heat.
• Seasoning Time: The time it takes to season firewood depends on several factors, including the wood species, the climate, and the stacking method. Generally, it takes at least six months to a year to properly season firewood.
• Stacking Methods: Proper stacking is essential for efficient drying. Here are some best practices:
  • Elevate the Wood: Stack the wood on pallets or timbers to allow air to circulate underneath.
  • Split the Wood: Splitting the wood increases the surface area exposed to air, speeding up the drying process.
  • Stack Loosely: Don’t stack the wood too tightly, as this will restrict airflow.
  • Orient the Stack: Orient the stack in a sunny and windy location.
  • Cover the Top: Cover the top of the stack with a tarp or roof to protect it from rain and snow.
• Wood Species and Drying Rates: Different wood species dry at different rates. Softwoods, such as pine and fir, tend to dry faster than hardwoods, such as oak and maple.
  • Oak: Oak is a dense hardwood that can take up to two years to season properly.
  • Maple: Maple is another dense hardwood that can take 12-18 months to season.
  • Pine: Pine is a softwood that can season in as little as six months.
• Moisture Meters: A moisture meter is a valuable tool for determining the moisture content of firewood. Insert the probes of the moisture meter into a freshly split piece of wood. A reading of 20% or less indicates that the wood is properly seasoned.
  • Cost: Moisture meters range in price from $20 to $100 or more.

Chainsaws vs. Both tools have their advantages and disadvantages, and the best choice depends on the specific task at hand.

• Chainsaws:
  • Advantages: Fast, efficient, powerful, ideal for felling trees and cutting large logs.
  • Disadvantages: Requires fuel and maintenance, can be dangerous if not used properly, more expensive than axes.
  • Best For: Felling trees, bucking logs, large-scale firewood production.
• Axes:
  • Advantages: Simple, reliable, no fuel required, less expensive than chainsaws, good exercise.
  • Disadvantages: Slower and more labor-intensive than chainsaws, not suitable for felling large trees.
  • Best For: Splitting firewood, small-scale wood processing, camping.

Data: Studies have shown that chainsaws can process wood up to 10 times faster than axes, especially when dealing with large logs. However, axes are still a valuable tool for splitting firewood and performing other tasks where precision and control are important.

Case Study: A small-scale firewood producer in Vermont uses a combination of chainsaws and axes. They use chainsaws to fell trees and buck logs, and then they use axes to split the firewood. This approach allows them to maximize efficiency while minimizing fuel consumption.

Cost Considerations and Resource Management

Wood processing and firewood preparation can be expensive, so it’s important to manage your resources wisely.

• Tool Costs: Chainsaws, axes, splitting mauls, wedges, and other tools can represent a significant investment.
• Fuel Costs: Chainsaws require fuel and oil, which can add up over time.
• Maintenance Costs: Chainsaws require regular maintenance, such as sharpening the chain, cleaning the air filter, and replacing spark plugs.
• Land Access: If you don’t own your own land, you may need to obtain permission to harvest wood from private or public lands.
• Transportation Costs: Transporting firewood can be expensive, especially if you’re hauling it long distances.

Tips for Resource Management:

• Review Your Owner’s Manual: Your owner’s manual is a valuable resource for information about your specific model of chainsaw.
• Practice Starting Techniques: Practice starting your chainsaw in a safe and controlled environment.
• Inspect and Maintain Your Tools: Regularly inspect and maintain your tools to ensure they are in good working order.
• Seek Professional Help: If you’re not comfortable performing certain repairs or maintenance tasks, seek help from a qualified technician.

Additional Resources:

Learn more