What Is a Carburetor?


The fuel system in a vehicle features many parts that help store and supply the engine with the fuel it needs to run. Gasoline gets mixed with air, and this mixture burns inside cylinders to generate power that gets the car moving.

A carburetor is a part responsible for mixing these components in the right amounts so the combustion process can occur. While carburetors aren’t used in late-model vehicles, they were used for many years until the introduction of electronically controlled fuel-injection systems.

Keep reading to learn more about how carburetors work and how they were used to deliver fuel to engines of many vehicles through the years.

How Does a Carburetor Work?

For a simple picture, a carburetor is a device that is fitted above an engine’s cylinders and has both an air and fuel pipe attached to it. A vacuum gets created, which is what the carburetor relies on to help draw air and fuel into the cylinders.

When air gets pushed down the pipe, it passes through a narrow opening known as a venturi. The air must speed up to pass through this area, which causes a drop in pressure. It’s this pressure that allows air to be drawn in through the fuel pipe.

Below and above the venturi are two valves that are important for adjusting the air-fuel mixture. The top of the carburetor features the choke, which is what regulates how much air is coming into the pipe. The second valve below the venturi is called the throttle, which can open and close to allow more or less air to enter the engine.

A more open throttle will allow more air to flow through the carburetor, which will bring in more fuel. This allows an engine to release more energy and have more power.

Inside the carburetor there’s a part known as the jet, which is an opening that allows fuel from the float chamber to mix with air before it enters an engine’s cylinders. Float chambers hold a small amount of fuel in them and allow it to flow to the jet as needed.

Carburetor vs. Fuel Injection

Carburetors were invented in 1888 by Karl Benz, one of the founders of Mercedes-Benz. It was a groundbreaking development for the industry at the time, and the technology was used by car manufacturers up until the late 1980s, when carburetors began getting replaced by fuel injection systems.

The main difference between carburetors and fuel injection systems is that fuel injection systems introduce an electronic process for delivering the necessary mixture for combustion. While modern injection systems began being widely used in the 1980s, NASCAR vehicles still featured carburetors up until 2012.

Fuel injection systems feature a range of parts that include a computer, fuel injectors, oxygen sensors and pressure regulators that work to ensure the right blend of air and fuel is delivered to the combustion chamber.

Electronic fuel injection allows for precise control over the amount of fuel being pushed into the cylinders. Fuel exits the fuel tank, traveling through lines toward the engine.

There is also the electronic control unit (ECU), which determines the exact amount of fuel the engine needs based on the volume of air entering the engine and the optimal air/fuel ratio determined by the specific manufacturer.

Signs of a Failing Carburetor

Although newer vehicles aren’t being produced with carburetors, there are older models on the road that still have them.

If you happen to be driving a car that has a carburetor, it’s important to know some of the signs that it might be failing. Over time, wear and tear can occur to the carburetor, and it might need to be serviced or replaced. Some symptoms include:

  • Reduced engine performance: The most common sign something’s wrong with the carburetor would be reduced engine performance. The carburetor wearing down can cause the air-fuel mixture to be off, resulting in a decrease in acceleration and power.
  • Backfiring/overheating: These are also common symptoms of carburetor failure. A lack of fuel in the air-fuel mixture can cause these two issues to happen, which in severe cases can cause severe engine damage.
  • Black exhaust: There should never be black smoke coming from the exhaust! This is likely a sign that the engine is using too much fuel or is fuel-rich. This can come from a carburetor that is worn and delivering excess amounts of fuel.
  • Difficulty starting: A common problem stemming from a worn carburetor is hard starts or difficulty starting the engine. Issues messing up the air/fuel ratio can result in these problems.

If you experience any of these issues, it’s a good idea to take your vehicle to a trained technician who can diagnose and fix your problem. You don’t want to cause more damage to your engine by ignoring possible signs of carburetor failure!

Learn More About Fuel Injection at UTI

Want the opportunity to work hands-on with fuel injection systems and other car equipment? The Automotive Technology program at Universal Technical Institute (UTI) teaches the fundamentals of maintenance and repair on a variety of vehicle types through courses that combine interactive labs with classroom learning.

You can graduate in less than a year7 with the skills you need for an in-demand career in the industry.1 As a bonus, you could gain the knowledge to make repairs on your own vehicle. Request more information today!

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