Briggs and Stratton Lawn Mower won’t Start After Sitting

You start your Briggs and Stratton mower like every other Saturday morning, but it won’t start this time. You try again and again, but it’s no use.

You begin to feel frustrated and a little bit defeated. You know you should have gotten that tune-up last month as your friend told you to, but you never got around to it.

Now what?

Briggs and Stratton Lawn Mower won’t Start After Sitting

Troubleshooting the Engine

Based on what you’ve told us, there might be an issue with the engine. Here are a few troubleshooting tips to try:

  • Check the spark plug. It might be dirty or corroded, preventing the engine from firing.
  • Ensure the fuel tank is full and the fuel filter is clean.
  • Examine the air filter. The engine won’t get enough air to start if it’s clogged.
  • Ensure the recoil starter is in good condition and the cord is securely attached.
  • If you’ve tried all these things and the engine still won’t start, it might be time to take it to a mechanic.

Checking the Gas and Air Filters

Before you do anything else, it’s a good idea to check the gas and air filters. If either is clogged, it can prevent the lawn mower from starting.

The gas filter is located on the fuel line and is responsible for keeping dirt and debris out of the carburetor. If it’s dirty, it can cause the engine to sputter and die. 

On the other hand, the air filter is responsible for keeping harmful particles out of the air intake. If it’s clogged, the engine won’t be able to get enough air, and it will also die.

Checking the Spark Plug

You may be wondering where to start. The first thing you should check is the spark plug.

If the spark plug is dirty or wet, it can cause the lawn mower not to start. Remove the spark plug and clean it off with a wire brush. Make sure it’s dry before you put it back in place, and try to start the lawn mower again.

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Cleaning the Carburetor and Fuel Tank

If the spark plug and air filter are in good condition, but your Briggs and Stratton lawn mower still won’t start after sitting idle, you should check the carburetor and fuel tank. The most common cause of an engine not starting after a long period is bad gas or a dirty fuel tank.

Before you try cleaning, turn off all power sources by disconnecting the spark plug wire from the spark plug. Then, remove the carburetor bowl nut and filter screen before cleaning them with carburetor cleaner or compressed air.

If your lawn mower is still not starting, check for clumps in the gas tank that could block fuel flow. If there are any, use a clean rag to remove the debris. Finally, replace the fuel filter if it’s clogged with dirt or debris. This will ensure that your Fuel Tank is free from debris and ready for use.

Replacing Parts if Needed

If all else fails, you may need to replace some of the parts of your lawn mower. The carburetor is often the culprit when a small engine won’t start, so you may need to replace it. You can find a compatible carburetor for your lawn mower online or at your local hardware store.

You may also need to replace things like spark plugs and air filters, depending on how long you’ve had your lawn mower. You can check these if they seem worn out or clogged with dirt and debris. A replacement is usually easy and inexpensive, so it’s worth looking at.

You should also look at the oil in your engine because if it’s too old, it can cause starting issues. It may be time for an oil change if it looks old or sludgy.

Preventing Problems in Future

It’s a good idea to take preventative measures to ensure your Briggs and Stratton lawn mower starts the next time you need it. The first and easiest step is adding a fuel stabilizer before storing the mower for an extended period. 

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This will help keep the fuel from breaking down and avoid issues like clogged carburetors or gummed-up fuel lines.

You should also periodically check the spark plug, air filter, and oil level to make sure they all still meet the requirements of your Briggs and Stratton lawn mower manual. 

Finally, ensure you are using a lawn mower battery that is in excellent condition and properly maintained. This will help keep your lawn mower running at its best when needed.


If your Briggs and Stratton lawn mower won’t start after sitting, the likely culprit is the carburetor. The carburetor on a Briggs and Stratton lawn mower needs to be cleaned and adjusted periodically to ensure that the lawn mower runs smoothly.

You can clean and adjust the carburetor on a Briggs and Stratton lawn mower by following these steps:

  1.     Remove the air filter and housing.
  2.     Remove the four screws that hold the carburetor in place.
  3.     Clean the carburetor with a carburetor cleaner.
  4.     Adjust the idle screw and the high-speed screw.
  5.     Put the carburetor back in place and reattach the air filter and housing.
  6.     Start the lawn mower and check for proper operation.

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