How to Test a Lawn Mower Coil

You may have already face the problem that your lawnmower is not starting. It may happen because your lawnmower spark is not firing. To solve this problem, you need to replace the old plug with a new one.

However, it is always a good idea to check your lawnmower coil as it is an engine component and responsible to generate voltage for firing. Sometimes, your lawnmower engine coil can get damaged and need to replace.

In this case, to determine whether the coil is damaged or not, you need to go through coil testing. Testing the coil is very easy and you can do it by yourself.

Whatever, in this article, I will describe the detailed step on how you can test your lawnmower engine coil. After going through this article, you will be able to test your lawnmower coil by yourself.

Working procedure of a coil:

Basically, the coil is part of the engine that usually spins once you pull the machine’s starting rope. The coil is situated next to the flywheel. The permanent magnets that are responsible for generating voltage using the magnetic induction are mounted on the flywheel pass near the coil.

Without it, a wire remains connected to the spark plug and the coil for conducting current to the plug terminal. As a result, sparking happens.

Continuity test:

However, the coil holds a single wire that is wounded about a hundred times on a single core. It is not possible to uncover and test the core. In this case, a simple test named the continuity test can be done for testing the coil. To perform this test, you just need to pass a bit current through the wire.

After passing the current, you will be able to measure the resistance using an ohmmeter. If the resistance is between 2.5K to 5K, then you have to understand that the coil is intact. On the other hand, if you find the resistance is infinite, that means the coil has broken.

Whatever, you may have already understood that you need an ohmmeter. So, make it ready. You gonna use it after a few minutes.

Exposing the coil:

Now, for performing the coil testing, you need to find out the coil first. You will find the coil covered using an engine cover. Remove the cover by unscrewing it or somehow. You may need to dismantling in some cases.

However, I am assuming that you don’t know the coil and have no idea about how it looks like. In this case, just follow the wire that comes from the spark plug. The coil will remain attached to the wire that you are following.

Fixing the Ohmmeter:

You are supposed to be ready with your ohmmeter. Now, set the ohmmeter resistance to 20K ohm. Here, “K” means kilo that stands for thousand. However, if you own a multimeter, keeps its dial on the 20K. After that, you need to insert both of the leads into the jack. There are two leads: red and black lead. Insert the black one into the ohm marked jack and the red one into the common jack.

Then, touch the lead together and check the meter before you start testing the coil. After touching both of the leads, the reading should be 0 or close to it. Again, the reading should be 1 if the leads are not touching together.

Testing approach:

Firstly, you have to find out the coil and also disjoin all the wire that is attached to the coil except the spark plug wire. You need to pull and off other parts of the spark plug wire. Keep the wire away from the spark plug.

Then, you have to insert the red leads of meter inside of the spark plug boot for touching the metal plate that is mounted in the deepest part of the spark plug boot. For ensuring contact, you may scratch the lead on the metal plate.

After that, you need to touch the metal coil housing with the black lead of your meter. Then, watch the result. If you see the result between 2.5K to 5K into your meter’s display, this means your coil is fine. Again, if you find the result is infinity or 1 or the needles of the display jumping far right of the scale, this means that your coil is damaged.

In this case, you have to replace your lawnmower engine coil with a new one as soon as possible.

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