man using lawn mower

There are very few things that are more frustrating when, at the beginning of Spring, you pull your Briggs and Stratton Mower out, give it a rudimentary wipe down and pull the starter chord expecting it to roar into life – and nothing.

A Briggs and Stratton lawnmower engine needs fuel, air, and spark for it to start. Check there is gas, and it is not dirty. Rather than checking and cleaning the air filter, buy a new one and install it. Finally, check the spark plug. In most instances, these actions will repair the lawnmower.

Over 10million Briggs and Stratton lawnmower engines are built each year and sold in over 100 countries. These lower-cost engines are known for their reliability.

With proper care and maintenance, riding mowers can last a lifetime of mowing. If they won’t start, it is often something simple which the operator can fix.

Reasons Why Your Briggs And Stratton Lawnmower Won’t Start & How to Fix Them

Lawnmowers which have been sitting for a few months are prone to several potential issues which prevent them from starting.

A few typical problems may occur if no preventative maintenance has been undertaken on the Briggs and Stratton lawnmower at the end of the previous season.

Common problems and possible solutions causing the non-starting are:

  1. No Petrol
  2. Contaminated or old petrol
  3. Clogged or dirty air filter
  4. Damaged or worn spark plugs.

Let’s look at each of these items and some simple solutions to get your Briggs and Stratton lawnmower back into the garden doing its job.

No Petrol Will Mean Your Engine Can’t Start.

Sometimes the fix is as simple as checking whether the petrol tank is empty or not.

Check the fuel level, and if empty, first fill the tank and try again.

Contaminated Or Old Petrol Will Damage Your Engine

If your Briggs and Stratton lawnmower has been lying up for more than one month, it is a good idea to empty the petrol tank and refill it.

After laying up for a few months’ petrol begins to go stale or gummy; it will start to form carboxylic acid and gum, causing it to degrade.

Not only does this reduce the ignition qualities of the fuel, but the carboxylic acid also begins to attack the soft materials in the fuel system.

First to go will be the fuel lines that will lose their flexibility and become stiff and brittle. The next will be the primer “bulb” and carburetor diaphragm. Damage to the aluminum in the carburetor will occur if the lawnmower is left long enough.

Old, stale fuel is the main reason why most carburetors need to be replaced.

Most of the corrosion will happen while the lawnmower is stored. However, be very careful if the lawnmower does start in this condition, as very old stale petrol cam cause rapidly cause damage, and you may need to end up replacing the carburetor.

Check here if you need to clean the carburetor.

Clogged Or Dirty Air Filter Is A Possible Cause

To make the internal combustion engine of a Briggs and Stratton lawnmower work, it needs fuel and air to cause ignition in the cylinder chamber.

This produces high-temperature and high-pressure gasses, which force the piston down to start the combustion cycle.

A dirty air filter will prevent sufficient air from initiating ignition. The symptoms of a blocked air filter are that the lawnmower starts for a very brief period and then stops. Despite trying, it won’t restart

It’s not worth cleaning the filter, not only because replacement is very cheap but also the smallest damage or hole in the air filter will allow dirt or other debris to enter the carburetor.

Damaged Or Worn Spark Plugs May Prevent A Briggs And Stratton Engine From Starting

As the ignition source, the spark plug must be in good order, correctly adjusted, fitted, and connected. If any of these factors is incorrect, your lawnmower engine will lack power or not start at all.

If the fuel-air mixture is incorrect, a black oily deposit will develop between the electrode and the ground on the spark plug.

Another symptom that all is not well with the spark plug is that the end which connects to the spark plug lead is corroded or pitted.

To check the spark plug:

  1. Disconnect the lead from the end of the spark plug
  2. Take a sparkplug socket, insert it over the spark plug and gently loosen it (anti-clockwise).
  3. There will be initial resistance, and then the spark plug should start rotating.
  4. Remove the spark plug and check the electrode for black oily deposits. You can remove stubborn deposits with a small piece of emery cloth. Be careful not to change the gap between the electrode and the earth (also called the side electrode). You can also use a spark club cleaner Amazon Spark Plug Cleaners.
  5. Test the spark plug by using any of the available spark plug testers. Amazon Spark Plug Testers
  6. A lawnmower spark plug is not expensive, and if you have any doubt, replace it. Amazon Lawnmower sparkplug.

Ensure it is the exact specification as the existing plug installed in your Briggs and Stratton Lawnmower. The code is printed on the side of the spark plug.

Reinstalling the plug is a simple reversal of the process listed above. Do not overtighten the spark plug.

How To Prevent Your Briggs And Stratton Lawnmower From Not Starting After Sitting?

Prevention is better than cure. Carrying out an essential service and storage regime at the end of Summer will pay dividends when you want to start the engine at the beginning of the following summer.

At the end of the mowing season, carry out the following simple tasks, and your Briggs and Stratton lawnmower will hopefully give you years of faithful service:

  1. Petrol is expensive, so use a gas stabilizer instead of emptying the petrol from the tank.
  2. It’s a great idea to change the lawnmower’s oil once a season. An hour after you finish mowing for the last time, drain out the old oil and fill it back up with new oil. Use the correct oil for the model. If your lawnmower is fitted with an oil filter, then change this simultaneously.
  3. Replace the spark plug.
  4. If your lawnmower has a battery, disconnect it, and remove it from the mower. Depending on the battery model, it may also be a good idea to place it on a trickle charge for the off-season duration.
  5. Clean the lawnmower and check for any damage.
  6. Check the blades and if they are damaged, replace them per the manufacturer’s instructions. If you are not comfortable changing the blades yourself, take the Briggs and Stratton lawnmower through to your local lawn mower repair shop.


Briggs and Stratton’s lawnmowers are the gold standard for affordable mowers. These engines are also regularly used in other brands of lawnmowers. Being widely sold in so many countries means that spare parts and repair facilities are widely available.

Treating your Briggs and Stratton lawnmower with a bit of care and undertaking annual preventative maintenance will hopefully ensure many years of reliable service.


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