How to Test a Chainsaw Coil

A chainsaw coil is one of the most important parts of your chainsaw. A bad or broken coil can lead to a faulty saw that doesn’t work, so it’s important for you to know how to test your chainsaw coils yourself.

Follow these simple steps:

  • First, remove any debris from the area where the coil is located on the saw
  • Next, inspect the outside of the coil for signs of cracks or corrosion.
  • Thirdly, inspect the inside by removing screws and carefully prying away insulation with a screwdriver until you are able to see bare wire at its base. If there are no visible problems with either surface then it is likely that your issue lies in other areas.

If you are having problems using your chainsaw and it is the coil that is causing you issues, then it can be tested using a multimeter. To do this, here are 14 simple steps.


How to use a multimeter for testing a chainsaw coil

With your chainsaw’s user manual, try to make out the actual resistance reading of the tool. Find where the coil is placed on the chainsaw. Then, attach the multimeter’s positive and negative cords to the appropriate terminals on your chainsaw’s coil and then measure the resistance.

Make sure to follow the steps listed below –


Step 1: Protection

At the start, ensure that you are wearing competent eye protection as well as rubber gloves. Insulated pliers should be used because they will protect you from a threat like electrocution. Also, check that the chainsaw is switched off.

The ignition coil’s location on your chainsaw may differ from other models. However, in a lot of models, it is situated close to the distributor. At times, the coil is concealed with a plastic cover for safety reasons. To gain better access, take it off.


Step 2: Disconnect before testing the spark plug

A spark plug wire must be disconnected from your chainsaw’s spark plug. In a lot of models, the wires in question run through the spark plug to the distributor cap. Due to the fact that these wires are held together by a couple of bolts, they are quite easy to remove.

Hand tools are needed to be able to disconnect the wires. The chainsaw’s engine usually becomes hot, so ensure that you put on safety gloves all the while you’re doing this. You should also create at least 15 minutes for the chainsaw to cool so as to reduce the risk of injury.

If you can, try to see that the spark plug isn’t damaged by testing it. This will save you time in the future. Also, consider connecting the wires of your chainsaw’s coil to the plug tester as opposed to attaching the wires to the spark plug. To do this, you need the alligator clips grounded before trying to crank the engine to confirm if there are sparks in the gap of the tester.

This tester also helps to prevent dirt, debris, butterflies, twigs, and dust from coming in contact with the combustion chamber of the chainsaw.


Step 3: Unplug the spark plug

Remove the spark plug using a plug socket or wrench. You should also ensure that no debris or dirt falls inside the hole after removing the spark plug. If anything is left inside this hole, it might lead to damage to your chainsaw’s engine. You should close the opening, so nothing falls inside the combustion chamber of the machine.

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Step 4: Conduct a checkup over the primary ignition circuit of the coil

The primary ignition circuit of the coil must be checked. Your chainsaw’s coil normally comes with two circuits: the primary and secondary circuits. With this in mind, attach the negative and positive leads of a multimeter to the respective terminals of your chainsaw’s coil.

Some chainsaws have coils with their positive and negative terminals clearly marked with the + and – signs. However, some others come with two terminals with pins that are situated at the connectors. A chainsaw’s coil has an average resistance range of 0.4 – 2 ohms. However, you have to do some due diligence regarding the accurate readings of the chainsaw you own (you will find this in the user manual).

In the event that your multimeter reads zero, it shows that the coil has to be replaced as soon as possible due to the fact that it has shorted internally. Also, in case the multimeter shows a reading that is above the required level, it also means that the coil has to be replaced because it has become open.


Step 5: The coil’s secondary circuit should be tested

You must test your coil’s secondary circuit. For this to happen, attach the coil’s positive terminal to the multimeter. As well as this, also attach it to the terminal that connects to the chainsaw’s spark plug.

A coil’s secondary resistance range (on average) is from 6 thousand to 10 thousand ohms. However, you need to make use of your manual to confirm the right secondary readings of the chainsaw you own.

In the event that your multimeter reads zero, it shows that the coil has to be replaced as soon as possible due to the fact that it has shorted internally. Also, in case the multimeter shows a reading that is above the required level, it also means that the coil has to be replaced because it has become open.

If needed, repeat the last two steps (4 and 5).


Step 6: The fuel pump should be disabled

When checking your chainsaw’s spark plug, the fuel pump relay or fuse must be disabled before the engine is cranked. This ensures that you can look at the coil for sparks due to the fact that the chainsaw’s engine won’t start. Read your user manual to find out the location of your fuel pump.

If your fuel pump relay or fuse isn’t removed, it will lead to grave damage to the chainsaw given that fuel will flood the tool. Due to the fact that there isn’t a spark plug, the cylinders won’t fire while they’re being tested.


Step 7: Crank the chainsaw’s engine

Let’s assume that your chainsaw’s coil is working. Make an effort to crank the engine. This should send power to the spark plug and electric system of the chainsaw.


Step 8: Look out for sparks

In the event that you come across blue sparks inside the gap of the spark plug when trying to crank the chainsaw’s engine, it indicates that the coil is properly working. This blue spark is bright enough to be seen during daytime, so in case you don’t see it, you’ll most likely have to get another coil for your chainsaw.

On the other hand, if orange sparks are visible instead of blue, it most likely entails that your chainsaw’s coil isn’t supplying enough electricity to the spark plug. The likeliest reasons for orange sparks are a cracked coil casing, weak current, or merely a faulty connection.

However, if you don’t see any spark, it means that you have either done the test incorrectly or that your chainsaw’s coil is dead. Then again, the electrical connection might be faulty, so check that too.

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Step 9: Have the coil reinstalled

If required, you can get the coil reinstalled. All that is needed is to insert it into the opening from where it was initially removed and connect all the wires. You can then replace the plastic cover.


Step 10: Check the coil’s resistance

To test the coil’s resistance, get a multimeter. You then need to take out the coil from the chainsaw to gain easier access to the electrical terminals. Ensure that the chainsaw’s engine has been turned off and has cooled down before beginning this bench test. You then have to remove the connection between the distributor wire and the coil.

To remove it from the mounting, make use of a wrench. After this, plug the test leads into the multimeter with the help of the jacks. Remember that the multimeter should be set in an ohms position. You can then press the leads and the multimeter should show a reading of 0 ohms. The test leads can then be moved after this.

Remember to pay attention to the infinite reading being displayed by your multimeter. The ignition wire should then be detached from the chainsaw’s spark plug. A lead from the multimeter should touch the spark plug’s terminal while the other should touch the engine ground.

Firmly press the lead point on the multimeter to make sure they’re properly connected. In case the multimeter shows a dissimilar reading, then it could mean the spark plug isn’t working correctly and should be changed. Ensure that you don’t touch any point of the lead with naked fingers because if this happens, the multimeter will definitely provide inaccurate information due to the fact that it will factor in your body resistance, thereby falsely indicating the problem of a faulty spark plug.


Step 11: Look for the coil’s resistance specifications

You need to search for your coil’s resistance specifications. Each chainsaw comes with different resistance specifications. In the event that your coil’s reading is outside the normal range then it implies that it has been damaged.

If you observe the readings that appear on the multimeter, you ought to normally see a reading in the 2.5k – 5k ohms range that shows the wiring of your coil is intact. A reading of zero appearing on the multimeter shows that there’s no resistance or that the connectivity is perfect. A reading that shows one means complete resistance, but it could also mean no connectivity.

When testing your coil and the multimeter stays at one, it means that there isn’t any connectivity. It also means the coil is damaged and it has to be replaced as soon as possible.


Step 12: Conduct measurements after connecting the primary coil to the multimeter

The leads on the multimeter need to be positioned on the primary coil’s poles. Your chainsaw’s distributor comes with three different electrical contacts – one on each side and another in the middle. These contacts might be external or internal.

After this, put on the multimeter and put a lead to the outer electrical connections. The multimeter should show the primary winding resistance of your coil which should be recorded. The more recent chainsaw models come with contact configuration which can be quite different from the orthodox arrangement.

If you want to know what contact will actually tally with the primary winding, the chainsaw’s user manual should be consulted.


Step 13: Measure after attaching your multimeter to the chainsaw’s secondary coil

The leads on the multimeter have to be positioned on the secondary coil’s poles. One lead must be kept on an outer electrical contact. After this, the other cable must be placed in a position where its distributor wire establishes a connection to the coil’s inner electrical contact.

The multimeter should then show the secondary winding’s resistance and you need to carefully record the reading.


Step 14: Examine the measurements

Lastly, you have to determine if the measurements you took all fall in the specified range of your chainsaw. In case you observe that the secondary or primary winding is below or above the normal range, it most likely implies that the old coil will have to be replaced. You have to do this as soon as possible because if you don’t, there’s every likelihood of your chainsaw getting damaged.

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You have been able to complete the chainsaw coil test with the help of a multimeter. In case you don’t have any technical knowledge, you’re too busy or you just don’t want to do the additional work, you can decide to seek the help of professional mechanics to conduct the test on your behalf.


Frequently asked questions (FAQs):

  1. What regular maintenance should I conduct on my chainsaw?

You have to make sure that your chainsaw’s bar and chain are oiled enough. You ought to check if the chain has any obvious damage in or around its rivets and links. In the event that you find wear or stiffness in the rivets or links, you need to replace it.

  • When the chainsaw is being used regularly:

The chain should be regularly sharpened as well. Its tension and condition should also be checked. Look at its drive sprocket to see if there’s any wear and tear. Use chainsaw sharpeners to keep your chainsaw in top shape. The air intake ports must be cleaned at regular intervals – so should the air filter.


  • Weekly:

You have to file off burrs from the bars’ edges every week.

You also need to inspect the spark arrestor with your chainsaw’s muffler. If needed, it should be cleaned or replaced. During this time, the carburetor should also be cleaned and replaced if need be. Inspect the hose of your chainsaw’s fuel tank to see if there’s any damage. Try to replace it every month if you can.


  • Monthly:

At least once every month, empty the fuel tank so that you can thoroughly clean it. This also applies to the oil tank. The connections and cables of the chainsaw have to be regularly checked.


  1. What do I do if the chainsaw becomes flooded?

Extra gas isn’t needed if you have the problem of a flooded chainsaw.


  • Step 1:

Make sure you don’t prime the chainsaw. This is because the chainsaw already has adequate gas.

  • Step 2:

When two or more minutes have passed, you can decide to pull the cord while everything is on. This will include the throttle being pressed with the interlock. It is dangerous to crank any depressed chainsaw devoid of a working interlock, so you should seek the help of another person.

  • Step 3:

If this doesn’t work, give the chainsaw a break by putting it off. Also, switch off the throttle.

Pull or push the choke to ensure that it is in the required off position. Dislodge the spark plug and make sure the cord is pulled twice. After this, put the plug. You have successfully reset your chainsaw, meaning you can now start to clear the flooded engine.

  • Step 4:

A stalled engine is majorly caused by flooding. Since you have turned off everything, try to pull the cord of the engine eight times. After this, try to restart it without priming and with all the systems turned on.

  • Step 5:

You can now put the switch in an “on” position. However, the on position for the throttle is only a final resort. There are chainsaws that will tell you to alter the throttle. If your chainsaw is one of those, heed the instructions.

  • Step 6:

Since you’ve cleared your chainsaw’s engine of excess gasoline and have put the choke in its active position, you can then pull the cord of the engine multiple times until it pops once. Popping is a rapid response of the engine without any cranking. If the choke is on, don’t try another pop, or else you will have to deal with another flood.

  • Step 7:

In this position, put the choke in a dormant/inactive position (off). When this is done, pull the crank cord of your engine again. It should start after the first or second pull. Conduct an initial trial without the use of the throttle.


Final Thoughts

To draw this article to a close, I would hope that after you’ve read this detailed and comprehensive guide, you will be able to comfortably perform a coil test with the help of the multimeter. This should help you to save a considerable amount of money, effort, and time. Just ensure that you understand and follow the instructions and steps to the letter. Don’t also forget to make use of the right safety equipment.