Gone are the days when fuel flow is dependent on the partial vacuum state inside the combustion chambers. This method of feeding fuel into the combustion chambers has been made obsolete by the fuel pump. The former method is not very effective and only leads to wasting fuel. Reliance on the partial vacuum of the combustion chambers results in either excessive or scarce amount of fuel. This means that the fuel/air mixture will ether be rich or lean. In either case, fuel combustion will lead to production of pollutants such as carbon monoxide and nitrogen oxide. A fuel pump assures that there will be enough fuel that will be injected into the combustion chambers.
A fuel pump is not actually a very modern innovation. Its development has preceded the fuel injection system. However, in modern automobiles, the fuel pump is an integrated component of the fuel injector system. Without the fuel pump, the fuel injection system will not be able to effectively function. Without the fuel pump, the fuel injection system will be less accurate. It will not be able to control the right amount of fuel needed by the engine. The fuel pump is the one that drives the flow of fuel into the combustion chambers.
Basically, a fuel pump is a simple centrifugal pump that is analogous to the water pump of the engine cooling system. Unlike the water pump, the fluid that flows into the fuel pump follows a one-way path. Unlike the liquid coolant of the engine cooling system, the fuel is meant to be consumed inside the combustion chambers. The fuel will not return to the fuel tank. Hence, the fuel pump can be considered as a one-way pump. It may be powered by the same camshaft but unlike the water pump, the fuel pump does not allow fuel to re-circulate to the tank.
