Craftsman 42cc Chainsaw Coil Check (5 Pro Tips For Spark Fix)

Alright, let’s dive into diagnosing and fixing spark issues on a Craftsman 42cc chainsaw. I’ve spent years in the woods, from felling trees to processing firewood, and a reliable chainsaw is absolutely critical. A chainsaw that won’t spark is a frustrating experience, especially when you’re up against the clock or trying to beat the weather. While modern chainsaws are generally reliable, the ignition system, particularly the ignition coil, can be a common culprit behind a no-spark condition.

The “best option” for diagnosing a Craftsman 42cc chainsaw coil issue involves a systematic approach. This includes visual inspection, spark testing, coil resistance testing, and careful consideration of other related components. I’ll walk you through each step, drawing on my experiences and providing tips to ensure you get your saw back up and running smoothly.

Craftsman 42cc Chainsaw Coil Check: 5 Pro Tips for Spark Fix

Understanding the Importance of a Good Spark

Before we get our hands dirty, let’s understand why a good spark is so crucial. The ignition system’s job is to generate a high-voltage spark that ignites the air-fuel mixture in the cylinder. Without a strong, consistent spark, the engine won’t run. Period. This is the heart of the combustion process.

Combustion: The spark initiates the rapid oxidation (burning) of the fuel-air mixture, creating expanding gases that drive the piston.
Power: A weak spark results in incomplete combustion, leading to reduced power, poor fuel efficiency, and increased emissions.
Starting: A healthy spark is essential for easy starting, especially in cold weather.

Tip 1: Initial Visual Inspection – The First Line of Defense

The first step in diagnosing any chainsaw problem is a thorough visual inspection. This can often reveal obvious issues before you even pick up a tool.

Spark Plug Wire: Check the spark plug wire for any signs of damage, cracks, or fraying. A damaged wire can leak voltage, preventing a strong spark from reaching the spark plug. Make sure the wire is securely connected to both the spark plug and the ignition coil.
Spark Plug Cap: Inspect the spark plug cap for damage or corrosion. A loose or corroded cap can also interfere with the spark.
Ignition Coil: Look for any visible cracks, melting, or other damage on the ignition coil itself. Also, ensure the coil is securely mounted and that there are no loose wires.
Wiring Harness: Trace the wiring harness from the coil to the switch and look for any breaks, cuts, or loose connections. Rodents sometimes chew on these wires, especially if the saw has been stored for a while.
Ground Wire: Inspect the ground wire that connects the coil to the engine chassis. A loose or corroded ground wire can prevent the coil from functioning properly.
Flywheel: Examine the flywheel for any damage or debris that might be interfering with the coil’s magnetic field.

My Experience: I once spent hours trying to troubleshoot a chainsaw that wouldn’t start, only to discover a tiny crack in the spark plug wire that was barely visible. Replacing the wire solved the problem instantly. Now, visual inspection is always my first step.

Tip 2: Spark Plug Check – The Simplest Test

The spark plug is the most accessible component in the ignition system, making it the easiest to test. This is a vital step to rule out a faulty plug before diving deeper into the coil.

Removal: Carefully remove the spark plug using a spark plug wrench.
Visual Inspection: Examine the spark plug for signs of fouling, carbon buildup, or damage. A fouled plug can be cleaned with a wire brush, but a damaged plug should be replaced.
Spark Test: Connect the spark plug to the spark plug wire and ground the electrode against the engine block. Pull the starter cord and observe the spark at the electrode. A healthy spark should be bright blue and consistent. A weak, yellow spark or no spark at all indicates a problem.
Replacement: If the spark plug is fouled, damaged, or produces a weak spark, replace it with a new one. Make sure to use the correct spark plug for your Craftsman 42cc chainsaw (refer to your owner’s manual). I typically use Champion or NGK plugs and have found them to be extremely reliable.
Gap Adjustment: Before installing the new spark plug, check and adjust the gap using a spark plug gap tool. The correct gap is usually around 0.025-0.030 inches (0.6-0.8 mm).

Data & Insights: I’ve found that a spark plug’s condition can tell you a lot about the engine’s health. For example, a black, sooty plug indicates a rich fuel mixture, while a white, ashy plug suggests a lean mixture.

Tip 3: Coil Air Gap Adjustment – Critical for Performance

The air gap between the ignition coil and the flywheel is crucial for proper spark generation. If the gap is too wide, the coil won’t be able to generate enough voltage to create a spark. If the gap is too narrow, the coil can rub against the flywheel, causing damage.

Location: The ignition coil is typically located near the flywheel, on the side of the engine.
Adjustment: To adjust the air gap, loosen the mounting screws that hold the coil in place. Use a business card or a feeler gauge (typically around 0.010-0.015 inches or 0.25-0.38 mm) to set the gap between the coil and the flywheel.
Tightening: Once the gap is set correctly, tighten the mounting screws securely.
Testing: After adjusting the air gap, retest the spark plug to see if the spark has improved.

Case Study: I once worked on a chainsaw that had a weak spark. After checking the spark plug and wiring, I discovered that the air gap was way too wide. Adjusting the gap to the correct specification made a huge difference, and the saw started right up.

Tool Specifications: A feeler gauge set is invaluable for setting the air gap accurately. Digital calipers can also be useful for measuring the thickness of the feeler gauge or business card.

Tip 4: Coil Resistance Testing – Digging Deeper

If the visual inspection and spark plug test don’t reveal any obvious problems, the next step is to test the coil’s resistance using a multimeter. This will help determine if the coil is internally damaged or has a short circuit.

Safety First: Disconnect the spark plug wire from the spark plug before testing the coil.
Multimeter Setup: Set your multimeter to the ohms (Ω) setting.
Primary Resistance: Touch one probe of the multimeter to the primary terminal of the coil (the terminal where the low-voltage wire connects) and the other probe to the coil’s ground terminal (usually the mounting bracket). The primary resistance should typically be between 2-6 ohms. Refer to your chainsaw’s service manual for the exact specification.
Secondary Resistance: Touch one probe of the multimeter to the spark plug wire terminal of the coil and the other probe to the coil’s ground terminal. The secondary resistance should typically be between 2,000-10,000 ohms. Again, refer to your service manual for the exact specification.
Interpretation: If the resistance readings are significantly outside of the specified range, the coil is likely faulty and needs to be replaced. A reading of zero ohms indicates a short circuit, while a reading of infinite ohms indicates an open circuit.

Measurements & Statistics: In my experience, a coil that has significantly lower resistance than specified is often shorted and drawing excessive current, which can damage other components in the ignition system.

Personalized Story: I remember one time, a friend of mine was convinced that his chainsaw’s engine was completely shot. After testing the coil resistance, I found that it was completely open circuit. Replacing the coil brought the saw back to life, much to his relief.

Tip 5: Kill Switch and Wiring Inspection – Don’t Overlook the Basics

Sometimes, the problem isn’t with the coil itself, but with the kill switch or the wiring that connects it to the coil. A faulty kill switch or a shorted wire can prevent the coil from generating a spark.

Kill Switch Test: Disconnect the wire that runs from the kill switch to the coil. This will isolate the kill switch from the ignition system. Retest the spark plug to see if the spark has improved. If the spark returns, the kill switch is likely faulty and needs to be replaced.
Wiring Inspection: Carefully inspect the wiring harness from the coil to the kill switch for any breaks, cuts, or loose connections. Use a multimeter to check for continuity in the wires. If you find any damaged wires, repair or replace them.
Ground Connection: Ensure that the ground wire from the coil is securely connected to the engine chassis. A loose or corroded ground wire can prevent the coil from functioning properly.

Strategic Insights: It’s often tempting to jump to the conclusion that the coil is the problem, but it’s important to rule out other possibilities first. A systematic approach to troubleshooting will save you time and money in the long run.

Wood Processing Context: In a wood processing operation, downtime can be costly. Having a good understanding of chainsaw troubleshooting and maintenance is essential for keeping your equipment running smoothly.

Understanding Green Wood vs. Seasoned Wood

While we’re talking about chainsaws and wood processing, it’s a good time to touch on the difference between green wood and seasoned wood. This distinction is crucial for both cutting performance and firewood preparation.

Green Wood: Green wood is freshly cut wood that still contains a high moisture content. It’s typically heavier and more difficult to split than seasoned wood.
Seasoned Wood: Seasoned wood has been allowed to dry for a period of time, reducing its moisture content. It’s lighter, easier to split, and burns more efficiently.

Relevance to Chainsaw Use: Cutting green wood can be harder on your chainsaw due to the higher moisture content and increased resistance. It’s important to keep your chain sharp and properly lubricated when cutting green wood.

Felling Techniques and Safety Considerations

Proper felling techniques are essential for safe and efficient logging. Here are a few key considerations:

Tree Assessment: Before felling a tree, assess its lean, size, and any potential hazards, such as dead branches or power lines.
Escape Route: Plan your escape route before making any cuts.
Notches: Use proper notching techniques to control the direction of the fall.
Back Cut: Make the back cut slightly higher than the notch.
Safety Gear: Always wear appropriate safety gear, including a helmet, eye protection, hearing protection, and chainsaw chaps.

Debarking Logs and Splitting Firewood

Debarking logs can help speed up the drying process and reduce the risk of insect infestation. Here are a few methods:

Hand Debarking: Use a drawknife or a debarking spud to remove the bark manually.
Mechanical Debarking: Use a log debarker machine for larger-scale operations.

Splitting firewood is a common task for anyone who uses wood for heating. Here are a few options:

Manual Splitting: Use a splitting axe or a maul to split the wood by hand. This is a good option for smaller quantities of wood.
Hydraulic Splitter: Use a hydraulic log splitter for larger quantities of wood. This is a much faster and easier option than manual splitting.

Benefits of Hydraulic Splitters: Hydraulic splitters significantly increase efficiency and reduce the physical strain associated with manual splitting. They are especially useful for processing large quantities of wood.

Drying Methods and Moisture Content Targets

Properly drying firewood is essential for efficient burning. Here are a few drying methods:

Air Drying: Stack the wood in a well-ventilated area and allow it to dry naturally. This is the most common and cost-effective method.
Kiln Drying: Use a kiln to dry the wood more quickly. This is a more expensive option, but it can significantly reduce drying time.

Moisture Content Targets: The ideal moisture content for firewood is around 20%. Use a moisture meter to check the moisture content of the wood before burning it.

Firewood Stacking and Storage

Properly stacking and storing firewood is important for maximizing drying and preventing rot. Here are a few tips:

Elevated Stacking: Stack the wood on pallets or rails to keep it off the ground.
Well-Ventilated Area: Stack the wood in a well-ventilated area to promote drying.
Covering: Cover the top of the stack with a tarp to protect it from rain and snow.

Costs and Material Specs

The cost of firewood preparation can vary depending on the tools and equipment you use. Here are a few estimated costs:

Splitting Axe: \$50-\$100
Hydraulic Log Splitter: \$1,000-\$3,000
Moisture Meter: \$20-\$50

Material Specs: The ideal wood species for firewood are hardwoods such as oak, maple, and birch. These woods have a high energy content and burn cleanly.

Timing Estimates and Skill Levels

The time required to prepare firewood can vary depending on the quantity of wood and the tools you use. Here are a few estimated timelines:

Manual Splitting: 1-2 cords per day (depending on skill level)
Hydraulic Splitting: 3-5 cords per day (depending on skill level)
Air Drying: 6-12 months

Skill Levels: Manual splitting requires a moderate level of physical fitness and skill. Hydraulic splitting is easier and requires less physical exertion.

Next Steps

Now that you have a better understanding of how to diagnose and fix spark issues on your Craftsman 42cc chainsaw, as well as some basic wood processing techniques, you can confidently tackle your next firewood project. Remember to always prioritize safety and use the appropriate tools and equipment for the job.

Summary of Pro Tips

Visual Inspection: Start with a thorough visual inspection of the spark plug wire, spark plug cap, ignition coil, wiring harness, and ground wire.
Spark Plug Check: Test the spark plug for signs of fouling, damage, or weakness. Replace it if necessary.
Coil Air Gap Adjustment: Adjust the air gap between the ignition coil and the flywheel to the correct specification.
Coil Resistance Testing: Test the coil’s resistance using a multimeter to identify internal damage or short circuits.
Kill Switch and Wiring Inspection: Inspect the kill switch and wiring for faults that could be preventing the coil from generating a spark.

By following these pro tips, I am confident you can diagnose and fix most spark issues on your Craftsman 42cc chainsaw and get back to your wood processing or firewood preparation tasks. Remember, safety is paramount, so always wear appropriate personal protective equipment. Happy sawing!

Craftsman 42cc Chainsaw Coil Check (5 Pro Tips for Spark Fix)