How to test a chainsaw coil with a multimeter: Step-by-step

If you have problems with your chainsaw coil, you can test it using a multimeter or a multitester. We will show you what to do in 14 easy steps.

How to test a chainsaw coil with a multimeter:

Read out the correct resistance reading of your chainsaw in the user manual. Locate the coil on your chainsaw. Connect the negative and positive cords of the multimeter to the negative and the positive terminals of the coil in your chainsaw and measure the resistance. 

A brief answer is convenient for those who are short of time, but it will not give you the necessary details. Scroll on to read the detailed 14-step guide.

How to Test Ignition Coils: Check Your Coil in 14 Easy Steps

● Step No. 1: Protection

First, you must ensure you have suitable rubber gloves and eye protection. It would be best if you used insulated pliers to prevent yourself from electrocution. Make sure that the chainsaw is turned off. It is essential to have these safety measures in place before you begin.

The location of the ignition coil may vary from model to model of the chainsaws. In most of the models, it is located near the distributor. Sometimes, a plastic cover is used to conceal the coil for safety reasons; take off the cover to get access to the coil. This is where my multimeter comes into play.

● Step No. 2: disconnect and test the spark plug

It would be best if you disconnected one spark plug wire from the spark plug of your chainsaw. In most models, these wires run from the distributor cap to the spark plug. Removing these wires is so simple because they are held in place by only one or two bolts.

It is important to remember that if the chainsaw is running, you risk serious injury.

You will need a set of hand tools to disconnect these wires. The chainsaw’s engine can be scorching, so make sure that you always have the safety gloves on. Allow your chainsaw to sit and cool down for at least 15 minutes to prevent serious injury.

• Understanding How to Test a Coil with a Multimeter

Now, we create an environment to test the coil. To understand how to test a coil with a multimeter, connect the multimeter to the coil and check the reading. If there’s no reading, the coil may be harmful. This is why having a multimeter and knowing how to use it is essential.

Testing the coil with a multimeter is a crucial step in this process. After the test, create a record of the results for future reference.

If possible, test the spark plug using a spark plug tester to ensure it is not damaged and save potential time later. You must consider attaching the spark plug tester to the wires of the coil of your chainsaw instead of connecting the spark plug back to the cables.

Grounding the alligator clips and then cranking the engine to see any spark in the tester’s gap would be best. Check the prices for a spark plug tester here.

The spark plug tester will also help you prevent dust, dirt, debris, butterflies, or twigs from entering the combustion chamber of your chainsaw.

● Step No. 3: Remove the spark plug

You won’t want to let any dust, dirt, or debris fall into the hole from where you have removed the spark plug.

Anything leftover inside the cavity will damage the entire engine of your chainsaw, so you must keep this hole covered with a piece of dry cloth to prevent anything from falling into the combustion chamber of your chainsaw.

If your spark plug does not look okay, this is an excellent replacement time. Here, you can find a new sparkplug for your chain saw.

● Step No. 4: Check the coil’s primary ignition circuit

Now, you must check the coil’s primary ignition circuit. The coil of your chainsaw has two courses: primary and secondary. Directly connect the multimeter’s positive and negative terminals to the positive and negative terminals of the coil of your chainsaw.

The coil of some chainsaws has a negative and positive terminal that is visibly marked – and +. Others have two terminals or two pins located at their connectors. The average primary resistance range of the coil of a chainsaw is 0.4 to 2 ohms.

Still, you must research for the accurate introductory readings of your chainsaw specified in your user manual.

If your multimeter displays a reading of zero, it is an indication that you must replace the coil at once because it has internally shorted in the primary windings of your chainsaw. If your multimeter displays a reading above the specified level, it indicates that you must replace the coil because it is open.

If you do not have a multimeter, you can find a good one here.

Another option would be to use a unique small engine ignition coil tester. You can find them here.

● Step No. 5: Test the secondary circuit of the coil

Now, you must test the secondary circuit of the coil of your chainsaw. It would be best if you connected the positive pin or terminal of the coil of your chainsaw to the multimeter. Also, connect it to the high-output terminal that goes to the spark plug of your chainsaw.

The average secondary resistance range of the coil of a chainsaw is somewhere between six thousand and ten thousand ohms, but you must research for the accurate secondary readings of your chainsaw specified in your user manual.

If your multimeter displays a zero reading, it indicates that you must replace the coil of your chainsaw at once because it has short-circuited. If your multimeter displays a reading above the specified level, it suggests that you will also have to replace the coil of your chainsaw because it is open.

If you do not have a multimeter, you can find one here.

Repeat step no. 4 and step no. 5 if needed.

● Step No. 6: Disable the fuel pump

It would be best if you disabled the fuel pump fuse or relay of your chainsaw before you try to crank the engine to check the spark plug of your chainsaw. This will allow you to check the coil for spark as the engine will not start. You must read the user manual to locate the fuel pump fuse or relay.

If you do not remove the fuel pump fuse or relay, it will cause severe damage to your chainsaw because it will be flooded with fuel. The cylinders will be tested, and it will not fire because there is no spark plug.

● Step No. 7: Crank the engine

Assume the coil of your chainsaw is working. Try cranking the engine now. This will provide power to the electric system and the spark plug of your chainsaw.

● Step No. 8: Check for sparks

If you see any bright blue sparks jumping inside the spark plug gap when you try cranking the engine of your chainsaw, it means that the coil of your chainsaw is working correctly.

The bright blue spark is visible clearly in daylight, but if you don’t see any spark, it means that you need to replace the coil of your chainsaw as it is malfunctioning. And if you see an orange spark, it means that the coil of your chainsaw is supplying insufficient electricity to its spark plug.

There are three possible reasons for an orange spark:

1. faulty connection,
2. weak current,
3. cracked coil casing.

If you see no spark, this indicates that you have performed the test wrong, that your chainsaw’s coil is dead, or that one or two electrical connections are faulty.

● Step No. 9: Reinstall the coil

Reinstall the coil of your chainsaw after replacing it if needed. Please insert it into the cavity from where you removed it and reconnect all its wires. Put on the plastic covers if you have removed any.

● Step No. 10: Test the resistance of the coil

To test the resistance of the coil in your chainsaw, which is called a bench test, take your multimeter and remove the coil from your chainsaw to get easy access to its electrical terminals.

Make sure that the engine of your chainsaw is turned off and that it has a chance to cool down before you perform the bench test. It would be best to disconnect the coil from the distributor wire.

Use a wrench to take it off from its mounting. Connecting the test leads to your multimeter by plugging them into its jacks would be best. You must set the multimeter on its “ohms” position.

Now, you can touch the test leads together. Your multimeter should read 0 ohms. Now, you can move the test leads apart.

– The Importance of Knowing How to Test a Coil

Remember, the coil is essential to your chainsaw’s ignition system. It creates a magnetic field that induces a voltage in the spark plug wire. This voltage creates a spark at the spark plug, igniting the fuel in the cylinder.

The precise timing of this spark is crucial for the engine to run correctly. If the coil is malfunctioning, it can cause various problems, including a lack of spark, a weak spark, or a spark at the wrong time. Therefore, knowing how to test a coil is essential for anyone with a chainsaw.

You can find a good one here if you do not have a multimeter.

You must note the infinite reading that your multimeter is displaying. Now, you must remove the ignition wire from the spark plug of your chainsaw. Touch one lead of the multimeter to the terminal of the spark plug of your chainsaw and the other lead to the engine ground.

You must press the point of the multimeter’s leads firmly to ensure they are correctly connected. If your multimeter now displays a different reading, it means that the spark plug of your chainsaw is not working correctly and needs a replacement.

Never touch the points of the leads with your naked fingers; otherwise, your multimeter will display inaccurate readings, including your body resistance, and falsely indicate a bad spark plug.

● Step No. 11: Find the resistance specifications of the coil

You must find out the resistance specifications of the coil on your chainsaw. Every chainsaw’s coil has its own unique electrical resistance specifications. When the reading of your coil falls outside of this specified range, then it means that the coil is damaged.

Look at the reading displayed on your multimeter. Ideally, you should see a reading of 2.5k to 5k ohms, which indicates that your coil’s wiring is intact and working correctly.

On the multimeter, the reading of “zero” indicates no resistance at all or perfect connectivity, while the task of “one” indicates complete resistance or no connectivity.

If you test the coil and the multimeter remains at “one,” it indicates no connectivity; your coil is faulty and must be replaced immediately.

● Step No. 12: Connect the multimeter to the primary coil and measure

It would be best if you positioned the leads of your multimeter on the poles of your primary lock. The distributor of your chainsaw has three electrical contacts, one in the middle and two on both sides. These electrical contacts may be internal, sunken in, external, or jutting out.

You must turn on your multimeter and touch one lead to each outer electrical connection. Your multimeter will display the resistance of your coil’s primary winding, and you must record this reading.

The newer models of the chainsaws have contact configurations that can differ from their traditional arrangement.

To find out which contact will correspond to the primary winding, you must consult your chainsaw’s user manual.

You can find a good one here if you do not have a multimeter.

● Step No. 13: Connect the multimeter to the secondary coil and measure

Now, you must position the leads of your multimeter on the poles of your secondary coil. You must keep one lead on one of the outer electrical contacts. Then, you must touch the other lead to the point where the primary distributor wire connects to the inner electrical contact of the coil of your chainsaw.

Your multimeter will display the resistance of your coil’s secondary winding, and you must record this reading carefully.

● Step No. 14: Check the measurements

Finally, you must determine whether the measurements you just made fall within the specified level of your chainsaw.

If the primary or secondary winding has a reading a little above or below the specified range, you must replace the old coil with a new one simultaneously because the current one is malfunctioning. Otherwise, your chainsaw will get damaged beyond repair.

Congratulations! You have completed the test of your chainsaw coil using a multimeter. If you have no technical knowledge, are short of time, or are unwilling to make the extra effort, call a professional mechanic to perform this test.

Frequently Asked Questions (FAQs):

1. What maintenance should I perform on my chainsaw regularly?

You must ensure the chain and your chainsaw’s bar get enough oil. You must check the saw’s chain for visible damage in its links and rivets. If you find any stiffness or wear in the links or rivets of the chain, then you must replace it immediately.

– When you use your chainsaw:

You must sharpen the chain regularly and check its condition and tension. Also, check the drive sprocket for wear and tear and replace it when needed. To sharpen your chainsaw, you can use a chainsaw sharpener; they are not very expensive. Check the price here.

It would be best to regularly clean the starter unit’s air intake ports of your chainsaw. You must also clean its air filter regularly.

– Weekly:

Each week you must file off any burrs from the edges of the bars.

Weekly, you should check the spark arrestor screen from the muffler of your chainsaw and clean or replace it if needed. At the same time, you should clean the carburetor and replace it if needed. Also, check the hose of your chainsaw’s fuel tank for any damage and replace it monthly.

– Monthly:

Once a month, you must empty the fuel tank and clean it thoroughly from inside. You must also open the oil tank of your chainsaw and clean it thoroughly from inside once every month. You must carefully check the cables and the connections of your chainsaw.

2. What should I do if my chainsaw is flooded?

If a flooded chainsaw is your problem, no extra gas is needed.

– Step 1:

Don’t prime your chainsaw again. Your chainsaw has more than enough gas at the right place.

– Step 2:

After a few minutes, you can pull the crank cord again with everything on, including the throttle pressed in with its interlock. Cranking a depressed chainsaw without a working interlock is dangerous without using a drop start, so ask for someone’s help.

– Step 3:

When it still does not work, let your chainsaw have a break by turning it off. Flip off the on/off switch. Turn the throttle off.

Push or pull the choke to the “off” position. Remove the spark plug, pull the cord twice, then replace the plug. Now your chainsaw is reset, and you can start clearing its flooded engine.

– Step 4:

Flooding is the primary cause of a stalled chainsaw engine. Now that everything must have been turned off, pull the engine’s cord eight times. Then, without priming, try restarting with all systems on.

– Step 5:

Now, set the on/off switch in the “on” position. The throttle “on” position must be turned on only as a last resort. Some chainsaws instruct you to tweak the throttle; do it if required. Put the choke to the “on” position. Everything must be back on.

– Step 6:

Now that you have cleared the engine of your chainsaw from too much “liquid” gasoline and set the choke in the “on” position, pull the engine cord several times until the engine “pops” 1 time. Pop is a quick audible response and jerk of your machine without cranking.

Don’t try more than one pop with the choke on, or risk another considerable flood.

– Step 7:

At this point, Place the choke in the “off” position.

Pull your engine’s crank cord again with the choke in the “off” position. The engine will start in 1 or 2 pulls. Try it first without using the throttle control.

Final remarks

To conclude this blog post, I would say that after reading the comprehensive and detailed step-by-step guide above, you can efficiently test the chainsaw coil using a multimeter. It will help you save a lot of money, time, and effort.

Just ensure you have carefully read, understood, and followed the manufacturer’s instructions that came with your chainsaw.

Also, don’t forget to use proper PPE.

Frequently Asked Questions:

• How often should I test the ignition coil on my chainsaw?

You should test the ignition coil on your chainsaw every 3-6 months to ensure it functions properly. More frequent testing may be needed if you use your chainsaw very often or notice any issues with its performance.

• What tools do I need to test my chainsaw’s ignition coil?

The primary tool you need is a multimeter. You may also need insulated pliers, a spark plug socket, a spark plug tester, and essential hand tools like wrenches or screwdrivers to access components. Safety items like gloves and eye protection are also essential.

• What are the key things to check when testing the ignition coil?

You need to check the primary and secondary circuits of the coil using a multimeter to see if their resistances fall within the manufacturer’s specified range. You must also visually inspect for sparks, check connections, and determine if replacement is needed based on test results.

• What should I do if there is no spark from the spark plug?

If there is no spark from the spark plug, the issue could be a bad coil, faulty electrical connections/wires, problems with other engine components, or an incorrectly performed test. Retest connections, repeat the steps or replace the coil if it is faulty.

• Is it safe for me to do this ignition coil testing myself?

Testing the ignition coil involves dealing with electricity and fuel components. If you follow safety precautions like PPE gear and disconnecting the spark plug, the test can usually be safely done DIY. But contact a professional if uncomfortable.