By: Author John Cunningham. Published: 2020/12/21 at 12:51 pm
Mower engines are quite compact, and 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 mechanic’s tip to prevent common carburetor problems. (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 mower’s air filter covers are rectangular in shape and employ easy tools and less access for on-the-fly air filter cleaning. A regular type of carburetor lives behind the air filter housing and is identified by its 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, with small metal components with levers and springs and the characteristic bowl shape under the carburetor body.
Carburetor – Standard carburetor type with the 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 onto the combustion chamber. What I have described are the standard and most common types of 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 of 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 lever 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 from reaching the carburetor; this often results in black smoke and poor performance. A common fix for many carburetor problems is gas bowl draining; it’s easy to do, and for many fixes, there is a poor running mower. Check out draining the gas bowl video here.
A blocked fuel line or fuel filter will prevent enough gas from reaching the mower. However, the most common type of 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 repair 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. Gumming is such a 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.
- About the Author
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John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.