Lawn Mower is Blowing Out Black Smoke

If you are seeing a stream of black smoke blowing out of your exhaust pipe, your lawn mower is running in a rich condition. In other words, it is getting too much gasoline and not enough air into the engine. This makes for an excessively rich condition and will eventually foul the spark plug and carbon up the cylinder.

The first easy thing to check is the air filter to make sure that it is not clogged with dirt and grass clippings. A restricted air filter will decrease the amount of air coming into the engine and can cause this very condition.

If you have a pre-filter, it can also cause the problem. These filters can be washed and reused in many cases. Use some mild dish detergent and hot water and then wring them dry and let them sit out in the sun to dry out.

The other culprit is usually a poorly adjusted carburetor or if you are at high elevations, the wrong main jet is in the carburetor. Many carburetors today have no adjustments, but you can change out the main jet on many models of carburetors.

Look at each area of your lawn mower to determine which of these is causing the problem and correct them if needed.

My Lawn Mower is Blowing Black Smoke

To understand this problem, you also must know that there are different color smokes that a lawn mower can blow out the exhaust pipe. Blue, black and white smoke are the colors that you would normally see and in this article we will concentrate on black smoke.

Black smoke means that the engine is running rich. Running rich means that the engine is getting an incorrect fuel/air mixture. It is getting more fuel than air and thus burning in a rich condition. A clogged air filter is often the culprit here.

Black smoke is normally a rich condition. In most cases the engine is getting too much fuel to burn and cannot burn it all thus making the black smoke. The engine could also not be getting enough air. Things that can cause this is an air filter that is very dirty or a setting in the carburetor or fuel injection that is incorrect.

Try removing the air filter and inspecting it for dirt buildup or grass clippings. If it is clogged, purchase another filter and install and then test the engine. Carburetor or fuel injection settings should be performed by a qualified lawn mower repair technician.

Each lawn mower engine smoke condition has its cause and by knowing what color to look for and the steps to take to correct it, you can cure the my lawn mower is blowing black smoke problem.