What Is a Fuel Pump?
Fuel pumps are pumps used to supply fuel to an engine or other fuel-burning process.
It is also called a fuel pump. Fuel pumps include the following types of pumps, but in general, the term “fuel pumps” is used to refer to the feed pumps that deliver fuel to the fuel vaporizer of an engine. It is responsible for sucking fuel from the fuel tank and transporting it to the injectors, where it is sprayed into the engine cylinders.
- Feed pump
- Priming pump
- Injection pump
- Supply pump
Uses of Fuel Pumps
In the past, fuel tanks were located higher than the engine, allowing fuel to flow naturally to the engine. However, due to the diversification of engine positions and the need to control fuel inflow, fuel pumps are now indispensable.
Therefore, fuel pumps are basically used in all vehicles where engines are used, such as automobiles, motorcycles, aircraft, ships, agricultural machinery, and construction equipment.
Principle of Fuel Pumps
A fuel tank consists of two components: the pumps and the motor. The pumps intake the fuel and the motor will pump combustion gases and these two components work simultaneously to deliver fuel to the engine.
First, when the ignition is turned on, the fuel pumps are activated and the blades of the pumps rotate to fill the fuel pumps with fuel.
The impeller inside the pump then begins to rotate as the motor rotates. On the outside of the impeller, a vane groove exists, and using a small gap, an overflow is generated in the pump. This pressure is used to dispense fuel from the pump chamber.
In addition, since fuel pumps are located near where fuel combustion takes place, any malfunction can have a significant impact on other parts of the system.
For this reason, fuel pumps are also equipped with a device that automatically returns fuel to the fuel tank in the event of a malfunction.
Types of Fuel Pumps
Fuel pumps can be broadly divided into mechanical and electric types. There are two types of electric fuel pumps: the out-tank type, which is located outside the fuel tank, and the in-tank type, which is located inside the fuel tank.
1. Mechanical Type
Fuel pumps are powered by the rotational motion of the engine. A diaphragm made of leather or synthetic rubber inside the pumps moves back and forth in response to the movement of the engine camshaft to pump Fuel Pumps.
In the past, mechanical fuel pumps were used in cars with a carburetted fuel injection system.
However, the electric fuel pump is now the most commonly used type due to the following disadvantages: fuel tends to leak from the diaphragm, the pumping force varies depending on the engine speed, and the engine power loss occurs because the pump is operated using the engine’s power.
2. Electric-Powered Type
Fuel pumps are powered by an electric motor to pump fuel. First, fuel is pumped by the electric motor and stored in the injectors at a constant pressure.
Then, an electric current is applied to the coil inside the injector that receives an electric signal for fuel injection, and fuel is sprayed at high pressure from the fuel injector.
Unlike mechanical fuel pumps, these pumps are powered by an electric motor, which allows them to pump fuel stably without loss of engine power. For this reason, electric fuel pumps are now the most commonly used type of fuel pumps.
There are two types of electric fuel pumps: the in-tank type, in which the pumps are located inside the fuel tank, and the out-tank type, in which the pumps are located outside the fuel tank.
The out-tank type has the advantage of easy replacement of the pump, but has the disadvantages of dangerous fuel splashing into the engine compartment in the event of a pump failure and the need for a return pipe to return fuel to the fuel tank.
In-tank Fuel Pumps are now the norm, as they do not have these disadvantages and have the advantage that the heat generated by the pump can be cooled by the fuel itself in the fuel tank.
Other Information on Fuel Pumps
1. Life Expectancy of Fuel Pumps and When to Replace Them
The service life of a fuel pump is said to be 50,000 to 100,000 km. However, technically speaking, the fuel pump also keeps running while the engine is running, so if the engine is running for a long time even if the mileage is short, as in a car that idles a lot, the service life will be shortened.
If the Fuel Pumps fail, no fuel will be delivered to the engine and the car will not start, so it is important to inspect and replace them regularly.
When replacing the fuel pumps, the rear seat and fuel tank are removed. The area around the fuel pumps is intricate with wiring and hoses, making it difficult to perform the replacement on one’s own. It is recommended that the fuel pumps be replaced by an auto mechanic.
2. Failure of the Fuel Pumps
The criteria for determining whether the fuel pumps have failed are as follows:
- A loud motor noise, such as a whirring sound, is heard while driving
- The engine does not start when attempting to start.
If any of these symptoms are observed, the fuel pumps may be malfunctioning. Contact a service provider immediately for inspection and replacement of the fuel pumps.