WHAT THE HECK IS A...Carburetor? - Chad Miller Auto Care

PLEASE NOTE THAT CHAD MILLER AUTO CARE DOES NOT WORK ON VEHICLES WITH CARBURETORS.

BUT…Just for the sake of education…

To know what the heck a carburetor IS, we must first explore what the heck a carburetor IS NOT. A carburetor is not:

A cyborg from the future that is sent back to the past to kill the woman that would give birth to a future leader against the machines
The thing that comes with Especial Numero Dos at your favorite Mexican restaurant
A single-celled organism that survives only in soda pop
Someone that verbally assaults 4-door sedans

He may or may not be back.

So…what the heck is it then?

A carburetor is an “old school” device that regulates the mixture of fuel and air that is heated in an engine. Some vehicles manufactured between 1950-1990 and ALL vehicles manufactured after 1990 have an electronic device called a fuel injector, which has the same basic function, but is much more efficient.

They don’t all look like this, but this one certainly looks like this.

How Does It Work?

Basically, your car runs on explosions from burning fuel and air. The faster your car is running, the more it is exploding. So how is the mixture of fuel and air regulated in a carburetor?

There’s a vertical air tube with a horizontal fuel float chamber attached to it.
- There is usually an air filter or cleaner at the very top of the vertical tube.
- The vertical tube has a slightly more closed off section in it called a venturi.
- Underneath the air filter, there is a swiveling valve called a clutch valve.
  - When the clutch is open, filtered air is allowed into the tube.
- At the bottom of the vertical tube, there is a swiveling valve called a throttle valve.
  - When the throttle is open, even more air is allowed through the tube.
The fuel float chamber has a float valve system in it to control the amount of fuel in the chamber.
- It works very much like a toilet—the float is connected to an arm, which opens or closes the valve, depending on the amount of fuel (or water in a toilet) in the chamber.
Air is drawn into the vertical tube, and when it gets to the venturi, the air pressure drops, causing suction. That is what pulls fuel into the tube from the fuel float chamber through an opening called a jet.
- The more air being drawn in, the more suction is created, the more fuel is mixed in, and the more explosions happen in the engine.

Hashtag BasicCarb

Fuel Injection

Like I mentioned before, a fuel injector has the same basic function as a carburetor, but does it in a more efficient way. A fuel injector is controlled by the Engine Control Unit (ECU). The ECU detects the air flow in an engine and activates the fuel pump. That moves fuel into the fuel injector, which sprays a fine mist of fuel relative to the amount of air flowing through the throttle into the engine’s intake valves. When you accelerate, it opens the throttle, which lets in more air and causes the fuel injector to spray more fuel.

There are a couple of fuel injection systems:

Throttle body fuel injection
- This type of fuel injection system came after carburetors. They are very similar to carburetors in that one or two injectors are located in a central throttle body that supplies fuel to the engine through the intake manifold.
Multi-port fuel injection
- This type of fuel injection system is newer than the throttle body system, and is even more efficient. This system has its own individual injector at each of the engine’s cylinders.