Lawn Mower Starts Then Dies – How to Fix it Fast!

Having a well-manicured lawn is the goal for most homeowners during the growing season. Lucky for us in the south, we get to mow all year round. Some love it some don’t. Either way, you’ll encounter lawn mower starting issues at some point during the season.

I created this guide on lawn mower starting issues with the emphasis on when a mower starts and suddenly dies right after. This is one of the most common starting issues I have encountered and have answered for people over the years.

Many people ask me through email or on FB with something to the like of “my lawn mower starts but won’t stay running” or “the lawn mower starts for a minute then stops”. Just the other day Stanley M. emailed me saying that his Briggs and Stratton lawn mower starts then dies, and asked what should he do.

Let’s start.

Common issues for when a lawn mower starts then dies right away

The carburetor of an engine has the primary role in the working of an engine. If the carburetor does not work properly, the engine will stop and turn off. The no working of the carburetor could be the reason the lawn mower starts then dying. 

A lot of other issues can be the reason for lawn mower dying while working. These are some most common issues in the mower if it starts then dies. 

  1. Carburetor problems
  2. Old gasoline 
  3. Blocked gasoline cap
  4. Too much oil in reservoir
  5. Defective spark plugs

Before entering a checklist of these issues, I will get to know the role and problems of the carburetor in the engine. As carburetor issues are the most found issue in the no working engines so it should be on the top of the checklist.

Let’s get a little knowledge about the carburetor, its working and issues, and then the tricks to resolve them on your own. 

Role of carburetor in engine of lawn mower

Each type of engine has a carburetor, no matter if it is a 2-stroke or 4-stroke, engine of a car, bike, or a yard lawn mower. All the gas-powered lawn mower engines are equipped with carburetors.

The function of the carburetor is to mix the air and fuel(gas) to convert it into the combustible form for running the pistons of the engine.

Carburetors are equipped with precise measuring to mix the right amount of fuel with oxygen. This process of precise mixing of the air and fuel is known as AFR (Airflow ratio).

Whenever you start a lawn mower engine, the gasoline moves from the tank through the gasoline hose and runs down to the carburetor first where the whole process of combustion occurs.

The gasoline bowl is equipped with a floater that controls the inflow and outflow of the gas. The gasoline moves from the tank to the carburetor and the air is sucked through the air vent that ultimately creates the pressure of the air inside the engine. 

The gas is atomized and mixes fuel with the oxygen from the air. 

The combustion mixture creation is the primary function of the carburetor that is then transferred to the spark plug chamber in its finest form.

As long as the steady flow of the combustion mixture of gas and air is continued inside the spark chamber, the engine shaft remains rotating and keeps the tools working.

So if the lawn mower starts then dies, there is a maximum chance that the problem is in the carburetor portion. As the primary engine working starts from the carburetor.

Here are some most common carburetor issues with their resolving strategies that are discussed below. Make sure to go through all of these tricks to fix the problem by yourself.

Carburetor issues includes

  • Dirty/Clogged carburetor
  • Loose carburetor
  • Worn-out carburetor
1. Dirty or Clogged Carburetor
Dirty or Clogged Carburetor

Most of the carburetors have their carburetor bowl on the downside and the screw of the bowl attachment is also present on the bottom of the bowl. That bowl has a hole that supports the continuous flow of air.

Clogging of the carburetor happens mostly in the temperate regions where the mower works around the year. Or it could be due to the no working of the mower during winters.

Sometimes the working of the lawnmower in the dirty lawn with the soil blowing, that hole in the bowl gets clogged and stops the airflow in the carburetor. The clogging of the screw will not let the air pass from underneath and regulate the downward movement of the gas.

This issue of the carburetor is the primary problem that causes the lawn mower to start then dies or sometimes the lawn mower won’t start.

How to clean lawn mower carburetor?

Remove the carburetor bowl by using the ½ inch plug wrench. Clean the clogged dirt from the bowl and the screw using a thin wire.

Dirty carburetor needs a good blowout with any aerosol spray can of carburetor cleaner. It will clean all the dirt inside the carburetor bowl and make it run smoothly.

I personally use the aerosol can for cleaning the carburetors after the winter or the onset of the mowing season. I use WD-40 Specialist Fast-Acting Carb/ Throttle Body cleaner for cleaning the carburetor. 

The cleaner I used has the effective solvent formula to break down the carbon contaminants and leave the carburetor clean and dirt-free. All you need is the jet sprayer applicator for spraying this aerosol in a target place.

Process of cleaning 

Unscrew the carburetor bowl and give it a clean. Here comes the need for aerosol target spraying for cleaning the screw and hole of the carburetor. 

The only care needed there is that while rescrewing the bowl with the carburetor is to not overtighten the screw. The over-tightening of the screw will strip out the threads of the seal and distort it completely.

Routine checkup to avoid more damage to the carburetor

For maintenance of the carburetor to ensure the continuous working of the engine in the yard or lawns, give a little spray of aerosol cleaner in the hole of the carburetor. The spraying will open up the holes completely and remove the dirt if present.

Remove the air filter every time you start the lawn mower. Make sure the filter is clean otherwise replace the air filter to allow the clean air entry to the carburetor. 

Make sure to do these two tasks every time you start the lawn mowers.

2. Loose carburetor

An unsuitable attachment of the carburetor does not allow the optimal flow of air and fuel inside A loose carburetor never lets the engine function properly. 

A loose carburetor does not allow the creation of the optimal air pressure in the bowl and insufficient atomization of gas.

How to fix it?

Make sure to check the carburetor if any dirt is present on it, clean it. To make the carburetor working clean it with aerosol cleaner. During the process of cleaning the carburetor, make sure the carburetor is tight enough to make the optimal flow of the air.

3. Worn-out carburetor

Worn-out carburetor problems are commonly found in the old-age mowers or the mowers that have served you for years and have gone through many repairs. 

Each machinery has age and it does not work effectively with that speed as the new one. Even the repair will not make it work smoothly. That is the time to replace that part of the machinery.

Similarly, in the case of lawn mowers, carburetors are the primary part of the engine that gets most of the cleaning and tunings. So the carburetors are the first ones to be replaced with a new one.

How to fix it?

First of all purchase a new carburetor and new oil. Get the carburetor cleaner and kit of tools to replace the carburetor. 

Remove the old engine oil by unscrewing the bolt on the bottom side of the engine and after removing all of the oil, put the new oil in the engine.

Before opening the carburetor, pinch the gas hose with a clamp to stop the flow of gasoline to the carburetor.

Unscrew the carburetor from the engine and screw a new one on the body with the new seal. Tighten the screw so as to provide the proper atomization of gas in the bowl.

Other issues why a lawn mower starts then dies 

1. Old gasoline

Gasoline mowers run on gasoline but the presence of the gasoline in the tank does not guarantee the smooth running of the mower’s engine.

The quality of the gas does also matters to ensure the continuous running of the engine. If the mower is not used for a while, the gas present in the tank converts into damage-causing residues due to continual evaporation.

That residue in the tank leaves the particles that clog the engine parts and stop them from working. It ends in the form of a restricted flow of gas which means the lawn mower starts then dies or lawn mowers run for a minute then stop.

How to fix it?

Fixing the issue of the old gasoline in the tank comes out in two forms.

If the amount of gasoline in the tank is less than half the tank, you can try filling the remaining portion of the tank with the new gasoline to dilute the impurities. 

In case of more than half a portion of the tank with the old gasoline, it would be best to drain out the old gasoline from the tank and fill it with fresh gasoline. 

In both of these cases, the best action is to add any fuel stabilizer. I personally use the Sta-bil Fuel System Stabilizer to prevent the clogging residues in the parts of the engine. 

Make sure to read the directions on the package to add the proper ratio of stabilizer in fuel.

2. Blocked gasoline cap

Gasoline tank caps have a hole to stabilize the air pressure in the tank. If that pressure is destabilized due to the blockage of that hole with any material, it will disturb the flow of gasoline to the carburetor and make the mower not work.

It can also be the reason lawn mower starts then dying. The vacuum created inside the tank makes the gasoline stops moving and stops the carburetor from working.

How to fix it?

Clean the hole of the cap with any thin wire and wipe out the dirt from the cap. If the cap is already beaten up completely, replace it with a new one.

3. Too Much Oil in the Mower’s Reservoir

If you have cleaned the carburetor but the engine is still not working, then there is surely a chance that the problem is in oil quantity.

It is commonly observed that humans by nature want to overfill the oil reservoir to get the smooth running of the engine. But this act cost them badly in the form of not working.

As a result, the white smoke coming out of the engine is a sign of excessive oil in the reservoir.

The white smoke coming out of the engine might run the engine for some time but it will die in a few minutes.

How to fix it? 

Fixing the issue of overfilling the oil reservoir is an easy task if you have the knowledge. If the reservoir has too much oil, you need to drain some oil. 

To drain out the extra oil you can use a siphon or top the mower and drain the oil from the mower from the hole where you put it in.

Make sure to check the level of oil in the reservoir that if the oil quantity is adequate for smooth running. After draining some amount, start the engine and check the smoke color and if it stays running it is ok to use.

4. Dirty or Defective Spark Plugs

Spark plugs have extreme importance in the gasoline engine to ignite the combustion mixture and run the shaft of the engine. 

The spark produced in the spark plug ignites the fuel and a small explosion will produce power that runs the parts of the engine. 

If that spark plug is faulty and not working or igniting, the lawn mower won’t start or die in a few minutes. 

How to fix it?

Spark plugs are commonly found on the easily approachable part of the engine. In the walk behind lawn mowers, the spark plugs are covered with black cable.

All you need is a socket wrench to open the spark plug. Commonly the spark plugs are coated with build-up dirt or bad oil so they stop working. You need to clean the spark plug with an appropriate cleaner to clean the dirt.

But if the carbon residues are found on the spark plug and it looks filthy and dark, it is better to replace it with a new one. It will cost much less and be easy to replace.

Tip on spark plug check

Spark plugs of any engine should be replaced with a new one every one to two years. In the case of a mower, it is better to replace it with a new one at the start of every spring season.

Replacing Your Spark Plug

Replacing a spark plug is the easiest job in managing the engine. Simply get out the old spark plug and remove the plug with the spark plug socket.

Use a spark plug gauge to measure the gap between the electrode of the spark plug and check the recommended gap size of the plug.

You can adjust the gap by gently pressing the curved electrode and measuring the gap through the gauge again.

After correcting the gap between the electrodes of a new plug, now you can install the new plugin the spark plug head. But tighten the plug enough to stop any leakage of fuel out of the hole.

When it’s Time to Call a Professional: Lawn Mower Starts Then Dies

If your lawn mowers start then die or start for a minute and stop, you should have tested all the above-mentioned methods to fix the problem. If the problem still remains the same then it’s time to call a professional.

The professional will look over the wiring or any engine problem and fix it. 

Additional tips

If your lawn mower is covered in warranty and is not much old then you should not cost the tools and kits by yourself. In this case, you should call the manufacturer and they will send someone right to your home and pick the mower.

Some weekend warriors have low knowledge and are lazy so they hire some professionals even for a minor problem and this fixing costs them higher than their thinking and they blame the company. However, it is their own laziness.

In case that the mower is not covered by warranty, then find some local small engine repair shop rather than going to professionals. These small shop owners can fix these issues in less time and cost.

Preventive Measures to Control Mower Problems

The best way to put you out of the worries of mowers is by adopting preventive measures.

These tips will let your mower run and work like a pro. It includes the tips for winterizing the mowers and spring maintenance of the mower.

The checklist includes:

  • Clean the air filter every time you work
  • Replace the spark plug every 1-2 year
  • Try to not keep the gasoline in the tank of the mower
  • Use a stabilizer with gasoline to keep the fuel fresh
  • Apply degreaser timely
  • Use dipstick and fill the oil reservoir accordingly
  • Check the carburetor regularly and clean it with cleaner spray

If you follow all of these measures, it will let your mower perform better with fewer maintenance costs. Additionally, it will let you avoid the headaches of picking the mower to a repair shop and improving the mower’s life.

If the issue is not resolved by the above-mentioned methods, don’t hesitate to call a professional as sometimes the do-it-yourself is not worth the time and energy.

Final Verdict

If your lawn mower starts then dies or the lawn mower runs for a minute then stops, this is the perfect guide for you. In this guide, all the easily implemented methods are discussed that cost much less to manage the problem.

Most of the mowers get fixed by cleaning the carburetor with any aerosol cleaner. But if the issue is not resolved, go through all the methods and checklist to find the actual problem and fix it accordingly.

I am hopeful that this guide will help you to resolve the issue as it does for me and fix the issue of lawn mowers that start then die.

Related Articles

Leave a Comment