Why is my lawn mower making a popping sound?

Asked By: Sumera Wapel | Last Updated: 3rd June, 2020
Category: automotive road side assistance
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A backfire is a popping noise caused by gasoline igniting outside of the combustion chamber of the engine.

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Likewise, people ask, why is my lawn mower engine popping?

A spark plug that is damaged, worn, or has an improperly set gap between its electrodes creates a weak spark. As a result, the fuel may not ignite in the cylinder, but it might ignite when it reaches the hot exhaust muffler. The result is a loud backfire. Poor spark also results in a mower that runs unreliably.

Also Know, why do lawn mowers backfire? The Cause. Backfires occur when burning fuel enters the engine or the exhaust. If pockets of unspent fuel enter the engine before the valves close or escape to the exhaust system, a backfire occurs. Unspent fuel ignites when a spark occurs in close proximity to the fuel pocket.

Similarly, why does my lawn mower pop when I turn it off?

Backfire, or more accurately "after fire" when it occurs when stopping an engine, is caused by unburned fuel/air mixture being ignited by the heat of the muffler. Allowing the engine to idle from 30-60 seconds before turning the key to the OFF position will generally prevent this after fire condition.

Why is my Briggs and Stratton backfiring?

Shutting off the engine at high RPM, causing fuel to pump through the engine for ignition. Gasoline that contains alcohol has a tendency to ignite easier, which can cause afterfire. Small engine muffler type and manufacture. Carburetor adjustment may not be properly set for correct engine performance.

22 Related Question Answers Found

Can backfiring damage engine?

An engine backfire occurs whenever the air-fuel mixture in your car combusts somewhere outside the engine's cylinders. This can cause damage to your car's exhaust or intake if left unchecked -- and it also means that your car's engine isn't making as much power as it should, and is wasting lots of fuel.

What causes a small engine to backfire through the carburetor?

Usually when the engine backfires through the carburetor when starting, something is wrong in the valve and rocker arm area. Remove the spark plug(s) from the engine. Put a clean small screwdriver into the spark plug opening so you can tell when the piston is at the top of the stroke.

What causes backfiring in small engines?

Small engines, like any other engine, backfire most likely due to ignition timing issues, or fuel not being fully burned during normal combustion. I would first make sure the engine' fuel mixture is not set too rich, and that the spark plug is properly gapped, not fouled and is producing a consistent spark.

What causes a car to backfire on acceleration?

Engine backfires can be produced by a vacuum leak, bad timing, problems in the ignition system, a faulty sensor, an exhaust leak, or some other system fault. The backfire is produced when unburned fuel ignites inside the intake or exhaust manifold instead of a cylinder.

Can a lawn mower explode?


Lawn mowers can explode as a result of catching fire or unauthorized changes and modding of the engine and the fuel system. Under normal use, chances of a lawn mower exploding are very low, but this can be further prevented by regular maintenance and service.

What causes a lawn mower to sputter?

Your mower pulls in air from outside and mixes it with gasoline for the proper explosion inside the engine. A dirty air filter inhibits the flow of air into the carburetor. Clean or replace the air filter to stop the mower from sputtering to a halt. Too much air can also cause problems for the engine.

What causes backfire?

A backfire is caused by a combustion or explosion that occurs when unburnt fuel in the exhaust system is ignited, even if there is no flame in the exhaust pipe itself.

How do you adjust the governor on a small engine?

To adjust the governor, you would loosen the screw on the bottom of the governor arm and push the governor arm so the throttle is wide open. Then you would turn the bottom "clip" (which is connected to the governor shaft) counter clockwise. This will set the governor shaft on top of the governor spool.

Why does my lawn mower backfire and not start?

Lawnmowers shouldn't backfire when you're trying to start them. This often is a sign that the mower is damaged in some way; for example, you might have run over a large rock or other obstruction. When a flywheel is broken, your mower might stutter or backfire when you try to start it, but it won't completely engage.

What causes lawn mower to lose power?


The primary reason your push mower may lose power is often dirt. There are two major locations to check out – the air cleaner elements, and the fuel system. The second possibility is dirt and water in the fuel system. This will cause build-up in the carburetor, inefficient combustion, sputtering, and power loss.

Can a spark plug cause backfire?

Another possible cause of your backfire is a spark plug refusing to “spark” when the exhaust valve opens. If the air/fuel mixture has become too rich, unburned fuel is left in the exhaust system. The misfired spark plug ignites the rich air/fuel mixture, causing a loud “bang” in the tail pipe.

What are the symptoms of a bad carburetor?

Symptoms of a Bad or Failing Carburetor
  • Reduced engine performance. One of the first symptoms commonly associated with a bad or failing carburetor is a reduced engine performance.
  • Black smoke from exhaust. Another symptom commonly associated with a problematic carburetor is black smoke coming from the exhaust.
  • Backfiring or overheating.
  • Hard starting.

What is an Intek engine?

Intek engines are making the riding mower experience easier, smoother and more powerful. Both engines boast an overhead valve design that ensure the engine runs cooler and cleaner, in addition to enhanced protection from dirt and debris with our patented Advanced Debris Management system.

What causes flames from exhaust?

This phenomenon is caused by an overly-rich air/fuel mixture, as unburnt fuel is ignited further down the exhaust system, producing a loud pop or even flames from the exhaust. The spark from the spark plug can only ignite a certain amount of air/fuel mixture, therefore the excess fuel is exhausted out of the cylinder.

What causes a Kohler engine to backfire?


A bad exhaust valve or too lean a fuel mixture will also cause an engine to backfire. For some reason Kohlers do seem to backfire more than other makes.

Why does my Kawasaki engine backfire?

One type of backfire that occurs in a 23 HP Kawasaki engine is caused by improper ignition timing. The ignition timing is off, resulting in engagement of the spark plug before the intake valve closes, igniting all the fuel in the cylinder, as well as all the fuel in the manifold leading down from the carburetor.