Mechanical vs Electrical Fuel Pump

In non-gravity feed designs however, the fuel is required to be pumped to the engine from the tank and delivered under low pressure to the carburetor or to the injection system under high pressure. Most often at times carbureted engines will use low pressure pumps i.e. mechanical, that are attached on the outside of the tank. In contrast to this, engines that are fuel injected will often use fuel pumps that are electrical and attached to the inside of the tank.


Mechanical Pump



Prior to the time when electronic injection was becoming popular and widespread, the engines in an car that were most carbureted used a form of mechanical pump to transfer the necessary fuel into the bowls of the carburetor.


Diaphragm pumps comprise a chamber whose volume is increased or decreased by the flexing of a diaphragm that is flexible, not dissimilar to the action of a piston pump. A check valve is located at the inlet and exit ports of the chamber to force the necessary fuel to flow in one way only. Special layouts change, but in the most common setup, the pumps actually are normally bolted onto the engine block or head, and the engine's camshaft has an additional eccentric lobe that controls a lever on the pump, either directly or via a pushrod, by pulling the diaphragm to bottom dead center. In this, the volume increased, causing pressure to decrease. As a result this allows the fuel to be shoved conveniently into the needed pump from the tank (caused by atmospheric pressure acting on the tank).



Electrical Pump



In an abundance of modern cars, you will now generally find an electrical pump inside the tank. The electrical pump is used and creates positive pressure shoving, the gas to the engine. The higher gas pressure increases the boiling point. Setting the pump in the tank sets the component least likely to handle gasoline vapor from the engine, submersed in a cool fluid. Another advantage to using an electrical pump is that it's more unlikely to start a fire. Even though electrical components can often trigger a fire, the liquid fuel won't combust simply because of the flammability limit.



The ignition switch does not carry the power to the electrical pump; instead, it activates a relay that will handle the current load that is higher. It's common for the pump relay to cease functioning and to become oxidized; this is not far more unusual than the real pump.






So as you can see, both types of pumps i.e. mechanical and electrical have their own distinctive pros and cons and can both be useful for a certain purpose. In this last paragraph we will briefly sum up the pros and cons of these two so you can make an educated decision in regards to a comparison.





A simple mechanism


Won't fail in the event of wiring falling off


No trouble supplying a proper amount of fuel to the engine


Can be prone to leaking gasoline


Needs to be properly maintained





Constantly maintains the pressure of the fuel


It is easy to remove the distributor


Easy to install


Requires proper wiring and routing of hoses if you want it to be efficient


Can be fairly expensive


Anthony Johnson Nascar   

About the author:

Anthony Johnson is the owner and President of Monza Motion, LLC which owns and operates two companies out of Hamilton, Ohio. Monza Auto Parts which is the retail side of the business and Monza Energy is the powerplant research and development division. Anthony is an avid motorsports fan and classic car collector. He has a passion for the Chevrolet Corvair, which is a car that has forever changed America. He has a degree in Computer Forensics and Network Security from SWFC and is considered an Information Security expert. Anthony has worked with the DoD and major financial institutions across the United States.



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