How To Fix A Lawnmower That Turns Over But Doesn’t Start

Mowing the lawn is one of those chores that never seem to end.

Whether you’re a professional that mows lawns for a living or an occasional gardener with a small home garden, you will need a reliable lawn mower to keep the grass looking neat and tidy.

How to Fix a Lawnmower That Turns Over But Doesn't Start

Eventually, you’ll no doubt be faced with a lawnmower that turns over but doesn’t start as it should.

Even with regular maintenance lawnmowers can be temperamental machines occasionally, so if your lawnmower doesn’t start you will need to know how to fix it.

There are a large number of reasons why a lawnmower might turn over but not start and thankfully, some of these are very quick and easy to fix if you know what to look for.

Others may be more complicated but identifying the problem is the first step to fixing it.

In this article, we will look at how to fix a lawnmower that turns over but doesn’t start as well as the potential causes.

What Can Cause A Lawnmower To Turn Over But Not Start?

There are a wide number of reasons why lawnmowers might turn over without starting, but the most common causes are problems with the fuel, air, or spark supply systems.

For the internal combustion engine that powers the lawnmower to work properly, it needs all three of these elements to be running correctly.

A fault in any one of them could result in your lawnmower turning over but not starting.

If your lawnmower doesn’t start, this means that your first action should be to check the fuel, air, and spark supply systems.

Luckily, many of the faults these elements can have are easy to fix.

Things To Check If Your Lawnmower Doesn’t Start

Now that we know that it is usually a problem with the fuel, air, or spark supply systems that result in lawnmowers turning over but not starting, let’s look at the potential problems in more detail.

Dirty Air Filter

Air filters in lawnmowers are responsible for ensuring that your motor gets all of the air it needs.

For ignition and combustion to occur, your lawnmower will need this air so if the filter is blocked in any way, it can result in not enough getting in and your lawnmower not starting. 

If you’re not sure where the air filter on your lawnmower is, you should check the manual that came with it.

Once you’ve located the air filter, remove the plastic cover so you can see inside.

Air filters commonly pick up grass, dirt, and other contaminants and these lead to air blocks. If your air filter is dirty and blocked, you should give it a good clean.

Removing all of the dirt from your air filter will reinstate the airflow to the engine.

With the air freely flowing again, your motor should have enough for the combustion process to correctly work and for the lawnmower to start.

Bad Spark Plug

In many cases, the reason for the engine of your lawnmower not starting is that it isn’t receiving enough spark for it to ignite.

Spark plugs provide this spark so the first step is to remove the spark plug for the lawnmower to see if it is at fault (Also check out Simple Steps To Gap A Lawn Mower Spark Plug).

You should take a close look at the spark element of the plug to see if it is clean and intact.

This is usually easy to spot and is easy to fix, too.

The Wire Of The Spark Plug Isn’t Connected Correctly

The second thing to check when you look at the spark plug is whether the spark plug wire is making a solid connection with the end of the spark plug or not.

If there isn’t a solid connection, this can affect whether your lawnmower starts or not.

You should check to make sure that the rubber cover of the spark plug is securely over the plug, too.

Fuel System Doesn’t Work Correctly

The fuel system is a complicated system that has a few different components that can fail and cause problems. Let’s run through some of these.

The carburetor can get blocked and gummed up easily if you’ve left petrol to sit in your lawnmower.

Like many car engines, your lawnmower needs to be run frequently and if you leave it standing with some petrol in, it can lead to a blocked carburetor.

A similar problem can occur in the fuel filter, as well. This can also become full of debris so you should also check out the filter.

While checking the filter, take a look at the clear container that is placed around the filter as if this is no longer clear and is instead completely dirty, it can also contribute to fuel system problems.

The best way to assess the fuel system is to check out the air filter and spark plugs first.

If you find that the air filter is clean and there are no problems with the spark plug, you should spray some starter fluid into the chamber where the air filter is located.

After doing this, if you find that the mower either starts or then starts and stalls, it’s very likely there is a problem with the delivery system of the fuel to the motor.

How To Fix A Lawnmower That Turns Over But Fails To Start

How to Fix a Lawnmower That Turns Over But Doesn't Start

Now that we know some of the most common problems that can cause a lawnmower to turn over but not start, let’s now look at some of the fixes.

How To Fix A Dirty Air Filter

If you check your air filter and find it is covered in dirt or debris, you should clean it.

The easiest way to do that is to turn the air filter upside down and tap it on a solid surface.

This should be enough to dislodge the larger debris.

If you have access to an air compressor, you can use this to blow out any dirt inside the filter. 

If you try both of these methods but the filter still appears to be blocked, you may need to replace it.

How To Fix A Bad Spark Plug

If after checking your spark plug you discover that there was a problem with it, there are a couple of fixes available to you.

The best option depends on the exact circumstances. 

Remove the spark plug and take a close look at the plug to see if there are any problems with the condition of the ceramic coating, the electrode, or the terminal that houses the wire.

If there are any cracks to the ceramic coating, or you find that the electrode is shortened, burnt, or missing, your best course of action is to completely replace the plug.

If the coating and electrode is intact but the spark plug looks dirty on the tip, this is an even easier fix.

The dirt could be working as an insulator that prevents a spark or connection from the wire, so you may find that cleaning it with a light solvent and a small brush will be enough. 

How To Fix A Spark Plug Wire That Isn’t Connected

If the wire that connects your spark plug and the starting mechanism isn’t making adequate contact, there are a couple of things you can try to fix it.

The first is to push down the rubber shroud that is around the plug so that it fits more tightly. 

Take a look inside the shroud to ensure that you can see the wire and enough of it is exposed to make good contact.

If the rubber shroud is in poor condition and is either worn out or ripped, you may need to replace either the shroud or the entire spark plug.

How To Fix A Fuel System That Isn’t Working

If your fuel filter is dirty, the best option is to replace it.

You don’t need to replace the whole system as you can often just replace the individual part that is causing the problem.

If it’s your carburetor that is blocked, this can be cleaned.

This can be a difficult and in-depth process to tackle so you may want to leave it to the professionals if you don’t have experience with taking apart and reconstructing carburetors.

Final Thoughts

In this article, we looked at how to fix a lawnmower that turns over but doesn’t start.

We hope the information and tips will help you.

Brian Freis