Starting an Idle Lawn Mower – 2024 Guide

If you are amongst those individuals who are into mowing their lawns on a regular basis then you might be well aware of the situation that you might have to face when your lawn mower does not start very easily. It is quite difficult to start an idle lawn mower during spring especially if it has been inactive since last fall. There are times when people get completely frustrated with this and seem to avoid the lawn mowing task. These are the times when people think that it would be better for them to have those electric mowers hat come with automatic on and off switches to give the machine a superb start.

Idle Lawn Mower

Idle Lawn Mower

After a very long cold winter or even after an extended span of time, just like all other individuals, even you can find that your lawn mower is not starting. Starting your idle lawn mower would seem like an exercise class. However, there are many individuals who indulge in figuring out the small issues of their machines themselves because they do not have the budget to get lawn equipment repair services or tools.

However, if you are doing the repair work yourself or you are taking the services of a lawn mower repair company, make sure that the initial steps for identifying the main problem with the machine are taken wisely and in the right way. The most basic step is identifying the main areas that need to be diagnosed in a malfunctioning lawn mower.  

Working on the Spark Plug

So why is it so difficult to start a mower engine that has long been inactive? Your main focus should be on inspecting the spark plug with the use of a microscope for finding the exact problem. Having a look at the tip of the spark plug with the naked eye will help you in understanding the problem. If at all, you find some kind of an issue with the plug, you can simply replace it with a brand new and clean dry plug. This would probably help you in starting your machine within a few seconds.

The major issue with the spark plug is in its ceramic insulator that tends to get damaged because of the machine being stored outdoors. With relative humidity and temperature cycles changing every day and over-time, micro-droplets tend to condense and then re-evaporate from the surface of the ceramic insulator of the spark plug. Every time the microdroplets form, they rearrange the minuscule carbon elements that were deposited in the spark plug when the engine was operated the last time. This growth of droplets that keep forming pushes the carbon elements together into pathways that are conductive and the ones that simply wind up offering an optional track for electric current when you start your machine.

Idle Lawn Mower

The carbon elements do not short out things. Rather, they offer a track with very low electrical resistance so there is absolutely no spark or if there is some spark, it has very little energy that would be insufficient for igniting the cylinder charge. The moment the machine starts, heat from burns within clears the issue in a few seconds. Thus, when you go to use the machine next week, it starts off very easily. One of the most basic solutions to this problem would be replacing the spark plug. However, there are other cheaper solutions available for individuals who do not want to spend a huge amount of money on buying a spark plug.

The Use of Hot Flame

Making use of hot flame that comes from a gas stove burner or a good quality propane torch can also help in starting an idle lawn mower. First of all, it is important for you to understand that there is a reason behind the ceramic insulator of the spark plug that surrounds the central electrode, being made of a specific material. It is made up of a material with surface properties that catalyze the heating and burning off of the carbon elements when the ceramic insulator gets very hot. This means that if your lawn mower is not starting then it is not hot enough.

Idle Lawn Mower

This problem can be solved by removing the spark plug from the machine a getting a very hot and clean flame fully prepared. This flame can either come from a butane lighter or a propane torch. It can even come from a gas burner stove. While holding one end of the spark plug preferably the end that connects to the wire, try sticking another end of the plug or the spark end to the hot flame for some time.

Ceramic Insulator

Keep rotating the plugin such a way that the central electrode is heated along with the ceramic insulator that surrounds it. The entire procedure will take just a few seconds. Once the spark plug is taken out of the hot flame, try having a look at the ceramic material that surrounds the central electrode.

This will help you in noticing that the ceramic insulator that surrounds the central electrode of the spark plug is fully bright and is completely different from its gray or off-white appearance earlier. This will have your spark plug up and running as new. Get it properly placed in the lawn mower and you will definitely have an enjoyable mowing session.

Initial Steps for Identifying the Idle Lawn Mower Startup Problem

It is important to note that minuscule engines do not tend to be beyond the limits of DIY enthusiasts. Below, we will be having a look at some of the most common areas that need to be checked if your idle lawn mower is not starting easily.

  • Check whether the machine has gasoline in it provided you are using a gasoline-powered lawn mower.
  • Check whether the engine of the mower has enough oil.
  • Also, Check if the air filter is completely neat and tidy.
  • Have you given the pull chord of the machine a minimum of ten to fifteen strong pulls?
  • Is the leader of the spark plug properly attached to it?
  • Have you tried pushing the primer bulb multiple times?
  • Was the machine tipped upside down? It is important to note that if the mower was tipped upside down that the combustion chamber might have been flooded with oil.
  • Confirm whether there are any cracks in the block of the engine.
  • Make sure that there is no water intrusion within the engine
  • Make sure that the machine’s pull cord is working fine and free. It is also important for you to ensure that the engine of the machine is rotating smoothly in off position.

Going through the above steps will help you in determining whether any of the above mentioned problems are preventing the lawn mower from starting. If none of these problems have struck your mower engine then it is time for you to get on to the next level of possible situations.

Other Possible Scenarios

The engines of lawn mowers, just like all the other engines in other machines, come with three important requirements for start-up and they are compression, ignition and fuel delivery. In case your idle lawn mower has a problem with any of these important requirements, it will not start. It is also possible that the mower will start but it will not work efficiently. With the lawn mower operating erratically, a major destruction of the engine would be on its way.

Verifying Ignition

As a general rule, the ignition mechanism of the lawn engine produces sparks or electrical impulses. These sparks ignite a kind of fuel and air blend directed towards the combustion channel of the engine. Thus, it is important for you to verify that the ignition system of your mower is functioning the way it is designed. You can do this by following the steps mentioned below:

  • Remove the lead of the spark plug
  • You can remove the spark plug by using a ratchet or wrench but make sure that there is no damage caused to the ceramic part surrounding the central electrode of the plug.
  • Now that the lead wire of the plug has been unscrewed from the mower engine, you must try reconnecting it to the plug.
  • Control the mower in a way that helps you in pulling on the start chord of the machine while holding the center electrode of the spark plug against that part of the engine that tends to be metallic. This is the part that is not covered with debris or paint.
  • Try giving the start chord of the mower ten to fifteen steady and slow pulls while having an eye on the tip of the spark plug.
  • Make sure that when the start chord is steadily pulled, a blue spark appears on the tip.
  • If you find a spark then you can come to the conclusion that ignition is the cause behind your mower’s no-start problem. Get to the next step.

Verifying Compression

Once you are done with the step of confirming that the mower engine is actually getting a decent spark, it is now time for you to make sure that all the internal parts of the machine are working properly and are creating enough compression within the combustion cabin of the mower engine. Here, it is important for you to note that compression in the combustion cabin is developed from the up-down movement of the crankshaft, rod and piston. With the piston moving towards the machine’s spark plug, there is an increase in compression within the cabin until the point of fuel or air ignition. Conversely, with the piston moving away from the machine’s spark plug, there is a kind of negative vacuum or pressure created in the cabin drawing in more of the fuel or air blend.

Mower Engine

Idle Lawn Mower

Measuring the compression of the mower engine is quite easy. You can make use of a special equipment called compression gauge for this purpose. You can use this equipment for measuring the compression of the mower engine simply by following some instructions.

  • First of all, you will have to screw the compression gauge threads into the spark plug hole of the entire to a point where it is tightened firmly.
  • Now you need to pull the start ripe in a fashion as if you were starting the mower.
  • Now stop polling the rope and have a look at the gauge dial for seeing the psi reading of the engine.
  • Here, it is important to note that engines are available in different power capabilities and designs but generally speaking, readings below 80 psi indicate that there is a compression issue.

If your lawn mower is not starting because of the compression issue then it is important for you to understand that this problem can result in expensive bills. The entire repair procedure requires dismantling the mower completely, it is something that can be achieved on your own provided you know the right procedure and have the right tools.

Verifying Fuel Delivery

As has already been mentioned above, the third and probably the most critical requirement is fuel delivery. Amongst the three problems mentioned above, fuel delivery to the engine is considered one of the most common issues behind your idle land mower failing to start. The best way of determining that fuel delivery problem is the main culprit behind your mower not starting is visualizing the circuit that gas needs to travel for making its way to the combustion cabin from the tank.


It is important to note that the three important factors of compression, fuel delivery and ignition are factors that need to be considered when your lawn mower is not starting after it has been inactive for a very long time. However, there are other problems in regards to engine exhausting cooling, valve condition and valve timing that can also take a toll on the proper working of the mower engine.