Fuel Injector vs. Fuel Pump

by William Kinsey
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Fuel pumps and fuel injectors are two essential parts of cars today. Both components have similar characteristics. However, they perform very different functions during an engine's normal operating cycle.


A fuel injector is usually three to four inches long with a diameter of one to two inches. An in-the-tank fuel pump is usually five to seven inches long with a diameter of four to five inches.


A fuel pump pressurizes fuel and sends it through the fuel line to the fuel injectors. The fuel injectors atomize the pressurized fuel and inject it into the combustion chamber.


Fuel pumps increase the pressure within the fuel system. Fuel injectors decrease the pressure within a fuel system.


Both fuel pumps and fuel injectors are powered by electricity from the car's electrical system.


The fuel pump will come on when the fuel pressure within the fuel lines drops to a certain level. Once that level is reached, the fuel pump shuts off. The cycle between on and off time for a fuel pump is measured in seconds. A fuel injector will open when It receives a pulse generated by the car's computer. The cycle for these pulses is measured in milliseconds.

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