The fuel pump pushes fuel to the carburetor which has a small bowl that holds the fuel. Inside this bowl sits what is known as the float (a type of valve that floats in the fuel) and when the right amount of fuel is contained in the bowl the float or valve senses this and shuts off.

The engine contains a vacuum (absence of air). When the pistons inside this engine move downwards this vacuum pulls the fuel from the carburetor, taking it through a number of tiny jets into the engine. The jets are tiny holes which the fuel is forced through and the pressure of this action vaporizes the fuel.

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This vaporized fuel mixes with air which has been pulled in by the same vacuum effect through the air filter, and the air valve, into the carburetor. The fuel and air mixture is then directed through the intake valves into the engine. The air contains oxygen which when mixed in the right proportions with the vaporized fuel will make a combustible material (meaning simply that it can be lit and made to easily catch on fire).

Okay:

1. The pistons in the engine move down.

2. The vacuum pulls the available fuel and air from the carburetor.

3. The fuel is pulled through tiny jets and is turned in to vapor.

4. The fuel/air mixture is pulled through the in take valve of the engine and is ready to be burned.