Types of Fuel Pumps

Fuel pump is an essential component of any internal combustion automobile engine. It serves as the mechanical heart of a car and maintains a steady flow of fuel from car's tank to its engine.

Generally, a carburetor that uses air vacuum is enough to direct fuel to the engine. However, a fuel pump does function more efficiently and can help the carburetor to do its job better. This article will discuss what a fuel pump is precisely and types of fuel pumps.

There are two major types of fuel pumps - mechanical and electrical fuel pumps.

Mechanical fuel pump: Mechanical fuel pumps came before their electrical counterpart. They are referred as diaphragm pumps.

• A gravity free fuel pump is located on the head of the cylinder or on the engine block, and a camshaft regulates it by moving the pump's lever up and down.

• Car engines with carburetor use mechanical fuel pumps to drive the fuel from the tank to the fuel bowl of the carburetor.

• As the cam shaft clicks the lever, the lever in turn forces a spring that sets other springs in motion till the diaphragm is forced down the bowl of the pump, increasing the level of fuel in the pump's fuel bowl.

• The pressure of the diaphragm enables the fuel to move up and out of the pump through an outlet. The fuel then gushes into the carburetor.

• There is a check valve at both the outlet and inlet parts to make sure that the flow is unidirectional.

• A mechanical fuel pump operates at a pressure about 4-6 pounds per square inch.

Electrical fuel pump: This type of fuel pump is present in modern cars. An electric fuel pump operates at a pressure of 30-40 pounds per square inch.

• They utilize the fuel injection systems to spray the fuel directly into the engine instead of allowing it to flow from the carburetor.

• This method is not only faster but also more fuel efficient because the injection system can control the flow of fuel that goes into the engine.

• However, this fuel system needs to draw the fuel from the tank at high pressure.

• The electrical fuel pumps consist of an electric motor connected to pump that aids to suck out the fuel and pump it to the engine.

• Nevertheless, having any electrical component close to the combustion engine can be dangerous as there's a probability of gas vapors escaping and even a small spark could cause a fire. Hence, electrical fuel pumps are located inside the fuel tank itself - submerged in the fuel to keep it cool and prevent it from excess heating.

There are two subtypes of electric fuel pumps:
In-tank electrical fuel pump: As the name suggests, an in-tank fuel pump is located inside the fuel pump.

• Placing a pump inside the tank makes it less likely to handle gasoline vapors farthest from the engine. Also, it is less prone to start a fire.

• In-tank fuel pumps provide a constant flow of fuel to the engine, and fuel not used is sent back to the tank.

• The fuel pump generates positive pressure in the fuel lines to force fuel to the engine.

• In an event of destruction, vehicles with fuel injectors are equipped with an electronic control unit that enables to shut down the electric fuel pump to prevent the fuel from leaking.

Inline electrical fuel pump: An in-line fuel pump is connected to the fuel line while being wired to the battery.

• This type of fuel pump, which is tubular in its structure, contains several pumping systems.

• During the transfer of the fuel from the tank to the engine, the fuel from the tank is taken inside the pump.

• A mesh screen filters the residue (if present in the fuel) before sending the fuel to the metering pump.

• The metering pump then pushes spins and scrambles the fuel to generate high pressure.

• The process dilutes and separates the fuel to make sure that it meets the standards before being pumped into the fuel rail through the fuel line.

• Here the fuel is sprayed as a fine vapor into the cylinder's intake chamber through a tiny nozzle.

• With advances in technology, an in-line fuel pump is made to be placed outside the tank without the risk of flaming.

Turbo pump: A turbo pump is devised to increase the pressure of the fuel with the goal of increasing engine's performance and power.

• Applications of these pumps include rockets and other high powered vehicle engines.

• Turbo pumps include certain kind of driving turbines combined with rotor-dynamic pump.

• Regardless of its potential uses, they are often considered challenging to design and loss of efficiency is considered to be common.

• Fuel is pumped into a chamber where it is forced to a higher pressure by the blades rotating along an axis.

• Possibly, turbo pumps are designed with different shapes to promote increased pressure and delivery of powered fuel to a specific location.

Two major designs are used to create turbo pumps:

• Centrifugal: In this the fuel is injected along an axis and the spinning rotors force the liquid to the edges of a widening diffuser.

• These types of designs can produce the highest pressure because of the unrestricted flow of liquid through the diffuser.

• Significantly, a centrifugal pump might be seen in vehicles that require a great deal of power, such as tanks and rockets.

• Axial: This type of pump usually produces greater efficiency with lower pressure.

• The difference with the centrifugal design is that the rotating blades force the fuel towards a particular location rather than depending on centrifugal forces.

• Axial flow pumps combined with other pumps is considered easier to utilize and design in machines that don't require large amounts of pressurized fuel.

The pump is the stimulant that sets the fuel running. So, choosing the right fuel pump contributes a great deal to the engine's performance efficiency.

Airtex Fuel Delivery Systems is the leading aftermarket supplier of mechanical and electric fuel pumps and modular reservoir assemblies (MRA). For over 50 years, the Airtex brand has been the benchmark of fuel delivery and cooling system components. Fuel pumps from Airtex is an OE replacement pump. Airtex fuel pump and mechanical pump models are available for old and new cars.