Mower engines are quite compact, locating components can be difficult, not to worry, this guide will clearly identify your carburetor, fill you in on what it does and the fastest way to find it. I also share a top mechanics tip to prevent common carburetor problem. (Gumming)
A mower carburetor is located behind the air filter on the side of the engine, opposite side to the muffler.
In this post you’ll learn how to locate and identify your lawn mower carburetor and your mower air filter.
Identifying The Mower Air Filter
A mower carburetor lives behind the air filter and is often hidden from view. So first we’ll locate the air filter, finding the air filter means we found the carburetor, make sense? The air filter is positioned to one side of the engine, makes and models differ as to which side. But no matter what engine or model, they all tend to use a black plastic air filter cover. Once you’ve located the cover, finding the carburetor is a ton easier.
Most mowers air filter covers are rectangle in shape and employ easy tools less access for on the fly air filter cleaning. A regular type carburetor lives behind the air filter housing and is identified by it’s shiny metal bowl shape, but we’ll look at carburetors a little later. For now check out these pictures and try to identify the air filter cover.
What Does A Mower Carburetor Look Like?
Most carburetors look very similar, small metal components with levers and springs and the characteristic bowl shape under the carburetor body.
Carburetor – Standard carburetor type with bowl.
If you had a carburetor in your hand you’d notice an opening front and back, that’s where air enters the carburetor and is forced through the venturi, drawing fuel from the bowl as it travels on to the combustion chamber. What I have described is the standard and most common type carburetor, but not all carbs look like this.
Briggs & Stratton carburetor and tank assembly – A common Briggs and Stratton carburetor fitted to the Classic and Quantum engines, it’s a plastic carb and metal gas tank assembly.
This type carburetor is somewhat similar, as it lives under the air filter and employs levers and springs to control engine rpm. However, it doesn’t use a conventional gas bowl, instead the gas tank assembly and carburetor work together to perform all the functions of a carburetor.
New Type Plastic Carburetors – It’s worth noting the latest carburetor types are plastic, they still live behind the air filter housing and employ levers and springs and a gas bowl. However the bowl may not be as pronounced as the traditional bowl.
Common Carburetor Problems & Fixes
Carburetors although small and insignificant looking are in fact very sophisticated and crucial to your mower engine performance. A mower engine requires a mixture of fuel and air in order to run. The ratio of fuel to air also known as the AFR (air fuel ratio) is 14.7 to 1 (written 14.7:1).
The carburetor is tasked with maintaining this ratio, and that’s no easy task. Fuel demands change as the engine cuts grass or idles or traverses up a steep hill, the carburetor needs to make adjustments immediately.
If the carb supplies too little gas to the mix, the engine loses power and/or dies. If on the other hand the carb supplies too much gas to the mix, the engine stumbles, blows black smoke and operates at reduced power. When the ratio is off, it may be the fault of the carburetor, however many times it’s not.
A blocked air filter will prevent enough fresh air reaching the carburetor, this often results in black smoke and poor performance. A common fix for may carburetor problems is gas bowl draining, it’s easy to do and for many fixes there poor running, mower. Check out draining the gas bowl video here.
A blocked fuel line or fuel filter will prevent enough gas reaching the mower. However the most common type carburetor issue is contaminated gas (old, dirty or water in the gas). The next most common carburetor problem is dirt in the fuel jet and emulsion tube.
The jets and tube are tasked with metering the fuel through small holes, as you can imagine when these holes are obstructed, the ratio is off. The most common repairs I make to mowers in a season is carburetor cleaning.
Old gas gums up the carburetor and causes a ton of easily preventable problems. I replace a ton of carburetors where because if gumming and it’s such an easily preventable issue. I’ve covered this common repair in this post “Mower stats then dies”, or check out the video library if you need video help with carburetors or other common mower problems.
This mechanics top tip – Use a gas stabilizer. Adding a gas stabilizer will prevent carburetor gumming over the winter hibernation months, come spring it’s pull and mow, Nice! Check out the gas stabilizer video here and you’ll find a link there to the stabilizer I recommend.