An automotive fuel system consists of everything between the fuel tank and the carburetor or fuel injection unit. This includes the tank itself, all the lines, one or more fuel filters, a fuel pump (mechanical or electric), and the carburetor or fuel injection unit.
With the exception of the carburetor or fuel injection unit, the fuel system is quite simple in operation. Fuel is drawn from the tank through the fuel line by the fuel pump, which forces it to the fuel filter, and from there to the carburetor where it is distributed to the cylinders.
When there is a problem starting or driving a vehicle, two of the most important checks involve the ignition and the fuel systems. You must have fuel and spark for the vehicle to operate properly. If the ignition system checks out there is spark, then you must determine if the fuel system is operating properly.