How to Fix a Lawn Mower That Won’t Start? (Troubleshooting)

How to fix a lawn mower that won't start and what troubleshooting method

It’s your fifth attempt to start the damn lawnmower that was pretty much unemployed during whole winter. You are itching your head in confusion. What happened suddenly you can’t understand. Gosh, is it another repair cost… Calm Down!

Before freaking out try some simple troubleshooting on your lawnmower. It could be due to many simple reasons that you’re missing. Let’s know about some tricks on how to fix a lawn mower that won’t start.

Lawn Mower Troubleshooting Methods.

Before calling for a repairman you can actually try a few things to fix it when your lawn mower won’t start. Just Like the garden lawn tractors, this tool can be sorted with troubleshooting done by you. So, here’s a list of ways you need to go through for sorting out whatever the problem.

Maybe the Filter Is Dead…

There’s this part of lawnmower that plays as the guard of carburetor and engine. So that no debris element such as dirt or grass clippings can enter. I’m talking about air filter guards. If you notice that your push mower won’t start, it could be because the air filter is clogged. There might be too much dirt for it to function and so, it’s preventing the engine from starting up.

To make sure such trouble happens less, one needs to replace the filter often. You should clean or replace foam filters every 25 hours of usage.  The process of replacement is a bit different depending on whether it is riding or push lawnmower.

For riding mower, you need to raise the parking bake after turning it off. While in push mower, you need to go into the plug and pull out spark plug wire. Simply get rid of filter from the housing. A paper filter is always replaceable.

While for foam filters you can use a solution of detergent and hot water to clean it. Once the dirt loosens up, wipe and let it dry. Use some motor oil for wiping the filter. That’s it, power up and the whirring sound should declare your engine’s fantastic condition.

Is Spark Plug the Culprit?

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Unfortunately, the whirring sound never arrived with first troubleshooting tip, what next? Well, spark plug is the following suspect. Just as its name declares, this piece literally creates a spark to ignite engine fuel.

Sometimes it could be loosened. Or there could be a disconnection as well as water coating disaster affecting. Carbon residue can also be a possible situation. And so, the spark plug is unable to work causing mechanism malfunction.

If this is the possible problem, you need to locate spark plug in mower’s front part. Check whether there are any such problems. You also want to have a look at the beneath electrode and insulator. Just eliminate plug wire below cap.

Use a tool to unscrew, socket wrench can help. And then have a look at whether any buildup is causing problems. Use some brake cleaner sprays in the plug. Give it a few minutes to soak well. Then use a clean fabric to wipe the area.

Reinstall everything back in reverse serial. Finally, tighten everything back and try starting the mower. You may also need to replace the spark plug if it is severely damaged.

Empty or Old Fuel in Tank.

One very common reason that your mower isn’t starting could be an empty gas tank. Now hear me out before saying, yeah, it’s too obvious. If you have been not using the mower for a long time, chances are that this part could be overlooked.

Also, even if there’s gas, it could be too old to work anymore. Sometimes due to this excess dirt and moisture gets trapped. Using a siphon pump make sure to drain the gas out of tank, especially if it’s been more than a month now.

Use some fresh fuel to refill it and add some stabilizer as well. This will make sure the gas does not get doomed too early. And also, the moisture build-up will occur less.

Other Common Reason.

  1. The engine might not be able to get enough fuel. Check intake system to solve the issue. Also have a look at the choke, throttle, primer button parts.
  2. There could be an oil level float switch if you own a new model. Sometimes due to very low oil levels, the system disables start-up mode.
  3. Starter rope trouble can be also the reason. Have a check on the flywheel brake part. Also, make sure that there is no sort of jamming in the blade.
  4. Check whether there has been any mistake in fuel use. Are you sure it’s gasoline inside the engine? It could be diesel or kerosene as well. The smell is enough to let you know if that’s the case. Or you can ask someone who has a knowledge of how different these things smell.
  5. There can be shearing in flywheel or blade carrier’s key. The internal surface might be affected by damage and so, looking for a replacement might solve the issue.


You should always try any sort of troubleshooting after reading the manual of your mower. Also, make sure you disconnect spark plug before trying to clean underside of the deck. If you are not confident about handling parts, better call someone for help.

Avoiding Such Situation…

I understand there’s a shortage of time due to how busy people are getting with lots of chores to settle with. But, when you have the intention of keeping any possession for long term usage, a little bit of maintenance will always sound necessary.

And so, make sure you are making that effort to keep such issues away from your mower or tractor. The first thing you should care about is checking oil every month, depending on how many times you use vehicle.

Make sure you clean cooling fins on the cylinder head. Get rid of grasses and leaves occasionally from this area. The fin is responsible to keep your engine healthy by blowing heat away. So, no doubt this part is too crucial.

Again, depending on the usage, make sure you do some sharpening for blade. A tiny lawn requires once a year ritual for sharpening most probably.  Don’t forget to drip light machine oil on drive and throttle areas. Focus on control cables. This will get rid of any unwanted seizing and corrosion.

Also, it’s a good idea to cut dry grass. When grass is wet it may stick on the deck ‘s under part. Mud and grime usually accompany too. And that reason is enough to clog several pathways. Making your mower’s engine struggle to work. You want to clean these areas with a hose. However, make sure you are not getting water inside the engine.


That’s all for how to fix a lawn mower that won’t start and some common maintenance to avoid such calamities. Hopefully, you’ll take good notes from today’s writing. There are many other ways to treat your unhealthy mower when it does not start.

But also, it could be a severe problem as well. So, if after trying a few common troubleshooters nothing seems to work, let professionals handle it. You don’t want to cause damage to any part so choose the safer route.

About Jeremy

Hello! My name is Jeremy Bloomberg. I have been passionate about carpentry and DIY. Over the years, my passion slowly turned into expertise and wider knowledge about electronics. I’ve been involved in numerous projects, both professional and personal. I want to share all I have learned with you. Welcome!

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