The internal combustion engine was first successfully designed by Nicolas Otto in the late 1800s, but its design--while better than earlier attempts--was still crude. A few years later, Karl Benz, a German engineer and founder of Mercedes Benz, developed the carburetor.
While engines seem to be complex, their operation is quite simple. The combustion of a fuel and air mixture inside a sealed cylinder converts stored energy into motion. Fuel and air gets introduced to the cylinder by either carburetors or injectors. Carburetors have a series of fuel flow control systems in them, and the float bowl is the first in that line.
Carburetors have a small fuel storage tank that's integrated into their design to keep a ready supply of fuel at hand. The tank's fuel level is controlled by a float, much as a float inside a toilet tank. The amount of fuel available might be only a few fluid ounces or as much as a full cup, depending on the size of the carburetor and engine.
Whether on a small or large engine, fuel must be readily available at the point it enters the engine. Fuel in a gasoline tank is routed through a fuel line to the inlet of the carburetor. Pressure, either by a pump or by gravity feed, forces fuel into the temporary storage well, called a float bowl.
Once inside the inlet to the float bowl, the proper level of fuel is maintained by the float. The float is a buoyant device that is attached to an arm. This arm acts as a lever when it rises or falls with the fuel level, and at the opposite end of that lever is a valve that opens or closes the incoming fuel from the gasoline tank.
A float bowl and float are similar to the configuration found in a toilet tank. If the lid to a toilet tank is removed, an arm with a ball (or a "post" with a sliding float) will be seen. When the toilet is flushed, the water stored in the tank is released into the toilet. The ball drops and a water valve is opened. Once that cycle is flushed, the water refills the tank through the inlet valve. When the tank is full, the float causes the valve to close.
Their operation is simple and the reliability is high, but occasionally a repair is required. Floats are made of either brass or petroleum resistant composites. If a float becomes saturated or leaks, the fuel level could get too high. With a few tools, it is a simple component to replace.
Carburetors are becoming less common in automotive applications. In small engines, such as a riding lawn mower, more efficient technology of fuel management used in cars, trucks and motorcycles (electronic fuel injection) is not practical. The low cost and simplicity of carburetors will keep them in high demand for small engine applications well into the future.
How to Rebuild a Tecumseh Carburator
Tecumseh motors are known for their reliability and straightforward design. Mounted on everything from go-karts to lawnmowers to leaf blowers, Tecumseh motors...
How to Clean A Small Engine Carburetor
If your lawn mower, go-cart, tiller, or other small engine driven machine isn't running well or not running at all, it may...
How to Adjust Carburetor Floats
Your vehicles carburetor float is a vital part of the fuel system. It is the gauge which tells your carburetor how much...
How to Fix Lawn Mower Carburetors
A carburetor is a mechanical device that combines air and fuel in an internal combustion engine. The carburetor controls the flow of...
How to Clean the Needle Valve on a Carburetor
Most carburetors that use needle valves are the Rochester Quadrajet, Edlebrock and Carter AFB carburetors. The needle jet is a long thin...
How to Adjust Carburetor Floats on ATVs
Adjusting the carburetor float on an ATV is a necessary step in the process of rebuilding or rejetting the carburetor. Each time...
How to Free Up the Float in a Carburetor
You're driving along when suddenly, your vehicle chokes and sputters to a halt, starved of fuel -- or you are driving along...
How to Install a Carburetor Float Spring
All carburetors have fuel bowls. The fuel level in the bowl has a float, needle seat and spring that controls a fuel-inlet...
How to Repair a Small Engine Carburetor
Small engines, typically found on lawn mowers, ATVs, generators and pumps, have designs and components very similar to other four-stroke engines. They...
How to Fix Briggs & Stratton Float Carburetor
Briggs & Stratton manufactures small engines for lawnmowers and landscaping equipment. Fuel flows into a bowl in a float carburetor. The float...
How do I Adjust a Carburetor Float on a Marvel-Schebler?
Marvel-Schebler carburetors have been manufactured for many tractors and other industrial engines. Their simplistic design and heavy construction gives them many years...
How Does a Zuma Carburetor Work?
Yamaha's Zuma 50 scooter was fitted with a 14 mm Teikei-built carburetor to feed the 50 cc two-stroke single-cylinder engine. To many...
How Does a Toilet Flapper Work?
Open any toilet tank lid, and you'll see a collection of parts integral to the operation of the toilet. One such part,...