How To Test A Chainsaw Coil With A Multimeter

The main focus of this article is on how to test a chainsaw coil with a multimeter. Now, before we delve deeper into the topic, you should know that the ignition coil in a chainsaw is an important mechanism that transmits electricity to the spark plugs.

If the chainsaw doesn’t start when you crank the engine, it may mean that the ignition coil is malfunctioning and needs to be replaced. A multimeter can be used to check the coil.

Now, if you’re wondering how to test a chainsaw coil with a multimeter, the answer is given below in easy-to-follow steps.

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How to test a chainsaw coil with a multimeter

METHOD 1

Step 1 – Safety Measures

Before you begin the test, make sure to wear appropriate gloves to prevent yourself from getting an electric shock. Also, you must use safety goggles to keep your eyes safe.

Lastly, make sure the chainsaw is turned off, and the engine has cooled down completely.

Step 2 – Locate the Ignition Coil

Different model may have different location of the ignition coil, but usually, you will find it near the distributor. Sometimes it might be in a protective plastic casing, which you will have to remove before you move forward.

If you are not able to pinpoint it, you can always check the user manual to find where the ignition coil is.

Step 3 – Disconnect and Test the Spark Plug

This step helps you make sure the spark plug is working fine, saving you a lot of time and work. Also, no particles can enter the combustion chamber of the engine.

Disconnect: The spark plug needs to be disconnected from its wires. These wires usually run from the distributor cap to the spark plug and can be easily removed using handy tools.

Mostly, they are held in place with one or two bolts in place which need to be removed, and the spark plug detached.

Test: Use a spark plug tester for this step. Just connect the spark plug tester to the wires in place of the spark plug. This can be done using alligator clips. Crank the engine now to check for a spark between the tester’s gap.

Step 4 – Remove Spark Plug

With a spark plug socket, which is a special wrench, you need to remove the spark plug. At this point, make sure that no debris or fragments go into an exposed hole because the damage to the engine would be tremendous.

Use a cloth to cover the hole or with something appropriate.

Step 5 – Check Primary Ignition Circuit of the Coil

The coil in the chainsaw has two units, they are named as the Primary and the Secondary. First, you need to check the primary ignition circuit by connecting the negative and positive terminals in your coil to the negative and positive leads of the multimeter.

Either the coil will have visibly marked negative and positive terminals (+/-), or there will be two pins located at their connectors. Check the user manual to get the accurate readings you should have.

Usually, this ranges from 0.4 ohms to 2 ohms, but it may vary from model to model.

Non-standard readings

If you get a reading of zero, this means that the coil has internally shorted and needs to be replaced. If the reading is above the acceptable standards, then the coil is open, which again means that it needs to be replaced.

Step 6 – Check Secondary Ignition Circuit of the Coil

To check the secondary ignition circuit, connect the positive terminal of the coil in the chainsaw to the multimeter. In addition to this, connect it to the high output terminal that travels to the spark plug of the chainsaw.

Check the user manual for the acceptable standards that the second unit should have. The acceptable reading is from 6000 ohms – 10000 ohms, but it may vary from model to model.

Non-standard readings

If you get a reading of zero, this means that the coil has internally shorted and needs to be replaced. If the reading is above the acceptable standards, then the coil is open, which again means that it needs to be replaced.

Step 7 – Redo Step 5 and Step 6 For Each Coil

Step 8 – Disable Fuel Pump Fuse

Locate the fuel pump fuse with the help of the user manual of the model of chainsaw. The fuel pump fuse needs to be disabled before cranking the engine to check the spark plug.

By doing this, the engine will not start, and you will be able to check the spark plug.

Important note:

If you fail to remove the fuel pump fuse before cranking the engine, the cylinders will be tested but will not fire because of the missing spark plug.

This will result in the flooding of cylinders which can cause serious damage to the machinery.

Step 9 – Crank the Engine

Assuming that the ignition coil of your chainsaw is working, crank the engine. This will provide power to the machinery of the chainsaw and the spark plug too.

Step 10 – Check for Blue Sparks

When you crank the engine and you see blue sparks between the spark plug gap, this means that the coil in your chainsaw is working perfectly.

Faulty system

• Orange Sparks mean that the current to the spark plug is insufficient. This can be due to a cracked casing, a faulty connection or weak current.

• No Sparks mean that either the coil system in your chainsaw is completely dead or has a connectivity problem. Please keep in mind, if you have performed the test incorrectly, this can happen too, so make sure to check again.

Step 11 – Reinstalling the Coil

Once all the coils (if faulty) of the chainsaw have been checked and the faulty ones replaced, put it back in the cavity you removed it from and connect all wires and replace all covers.

METHOD 2

Step 1 – Perform an Ignition Coil Resistance Test (Bench Test)

You must turn off the engine of the chainsaw and wait until it is completely cool. Remove the coil from the cavity very carefully so that the wiring can be seen.

By using a wrench disconnect the coil from the distributor wire. Connect the test leads to the multimeter and set the position to ‘ohm’.

Test the leads by touching them to each other. The reading should be 0 ohm when the leads are touching and infinite when apart.

Remove the ignition wire from the spark plug in the chainsaw. Connect one lead of the multimeter to the terminal in the spark plug and the other to the engine ground.

Important note:

Press the leads firmly to make sure the connection is complete and stable. Also, make sure not to let your skin come in contact with the leads as it would result in a faulty reading because of the inclusion of your body’s resistance.

Step 2 – Check for Accurate Resistance Specifications

As each coil has a unique specific resistance level you need to find out the accurate specification for your coil. When the reading falls outside the specification it means that the coil is faulty.

Check the user manual for accurate resistance specifications. Usually it ranges from 2500 ohms – 5000 ohms, meaning the wiring is working perfectly.

Step 3 – Check the Primary Coil

There are three electrical contacts in the distributor, two on either sides and one in the middle. These contacts may either be protruding out (External) or concave like (Internal).

Touch one lead of the multimeter to each contact to check the reading. The reading should meet the acceptable standards mentioned in the user manual of the model of chainsaw.

If the reading doesn’t meet the acceptable standards it means the coil is malfunctioning and needs to be replaced with a new one.

Step 4 – Check the Secondary Coil

Place the leads of the multimeter on the poles of the secondary coil. Keep one lead on the outer electrical contact and the second lead on the connection point on the main distributor wire where it connects to the inner electrical contact in the coil.

Measure the reading and cross check with the user manual of the model. If the reading doesn’t meet the acceptable standards it means the coil is malfunctioning and needs to be replaced with a new one.

Step 5 – Reinstalling the Coil

Once all the coils (if faulty) of the chainsaw have been checked and the faulty ones replaced, put it back in the cavity you removed it from and connect all wires and replace all covers.

With these two methods and all the steps listed the testing of the chainsaw coil using a multimeter is complete.

The Verdict

By following the above steps in proper order and with accuracy you can easily check the coil system of a chainsaw with a multimeter and replace a faulty coil to have your machinery working again in no time.

If you are short of time or have no knowledge of the mechanics of a chainsaw, you can always hire a professional mechanic to help you. For further queries regarding how to test a chainsaw coil using a multimeter, you can write to us.

FAQs about how to test a chainsaw coil with a multimeter

1) Can you test a chainsaw coil with a multimeter?

Yes, you can. Just connect the positive terminal of the coil in the chainsaw to the multimeter. In addition to this, connect it to the high output terminal that travels to the spark plug of the chainsaw.

Check the user manual for the reading specifications.

2) Can a good resistance reading means a good and working coil?

Normally yes, though sometimes a damaged winding may sometimes make a connection and complete the circuit when cold and break the circuit when heating causes expansion.

3) What if my ignition coil gives very little sparks?

If the current flow and voltage is fine and you have little or no sparks, this means that your coil is faulty and needs to be replaced with a new one.

4) What if the coil tests good but still no sparks?

Check all the connections to the coil in reverse, especially the ground connections to the frame.

5) How many volts should my coil have?

The usual tools work on 12 volts, or if the coil has a ballast resistor then 7 volts.

6) Will the blue spark be visible in daytime?

Yes, the bright blue spark between a perfectly functioning spark plug gap is easily visible during daytime too.

7) How often should the spark plugs be checked and replaced?

It is advisable to replace annually or bi annually interval if you wish to. Also based on its functioning, that is perfectly or is faulty.

8) How many ohms are normal for ignition coils?

Most ignition coils have a resistance reading ranging from 0.4 ohm – 2 ohms, but you should cross check with the user manual of the model to be sure. If the reading is zero, it means that the ignition coils are faulty and need to be replaced.

9) What can cause an ignition coil to burn up?

The ageing of the insulating material is the main cause of the ignition coil burnout. When the high voltage doesn’t get a smooth output, the turbulence in the coil leads to a rise in temperature, which in turn escalates the ageing of the insulating material.

10) Why does the ignition coil short out?

If the spark plug or its wire has too much resistance or is open, there can be a rise in the voltage of the ignition coil output, which in turn burns through the coils internal insulation causing a short.

11) Should all ignition coil packs be replaced at the same time?

No, only the faulty coils should be replaced while the others continued. Older coils are better and more reliable if working optimally.

12) How do you know if the spark plug is faulty or the ignition coil?

During the test process, after cranking the engine if there is a spark between the spark plug gap but the machinery is still not working, this means the spark plug is faulty.

However, if there is no spark between the spark plug gap, it is possible that the ignition coil is malfunctioning and needs to be replaced.

13) How to make sure that the spark plug is firing?

Turn on the engine and keep pulling one wire at a time from the spark plug. If the idle speed of the motor drops with each wire pulled then the spark plug is working perfectly.

If the idle speed of the motor doesn’t reduce with a spark plug wire pulled then it is not igniting the fuel in the engine.

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