A fuel pump is a mechanical or electronic control mechanism that can supply fuel from the fuel tank to the fuel rail via a fuel filter. From there, the fuel is distributed to the injectors and injected into the combustion chamber of each cylinder of the engine. In older cars, the pump supplies fuel to the carburetor.
Type of fuel pumps
1) Mechanical Fuel Pump
A mechanical fuel pump uses positive displacement with a piston or diaphragm. In a circular motion, the pump absorbs the fuel, extracts it, then transfers the fuel to the carbohydrates and the engine and repeats this process.
2) Electric Fuel pump
The electronic fuel injection system in modern vehicles requires higher pressure, which is achieved in part by using an electric fuel pump instead of a mechanical module. The most common examples of electric pumps are given below:
- In-tank: Maximum new cars sold today use the fuel pumps in the fuel tanks. This helps to cool and safe the gas and the module.
- In-line: Easier to replace than the fuel tank pump. The pump installs in-line between the engine and the fuel tank and generally installs on the fuel system rail. They are usually installed under the car or in the engine compartment.
- Rotary Vane Type: Like mechanical pumps, rotary vane pumps use positive displacement to move fuel. In a rotary vane pump, a rotor with a “vane” moves abnormally in the cavity. As it is unusual, it creates a crescent-shaped space for the fuel inlet. When the rotor is in motion, the blades cut a small amount of fuel and are released as the fuel passes through the outlet valve. Types of vane pumps include roller vane, sliding vane, flexible vane, and reciprocating vane.
How mechanical Fuel Pump works?
The mechanical fuel pump is driven by a camshaft or a special shaft powered by a crankshaft. As the shaft rotates, a cam passes under the rotary lever and pushes it up at one end.
The other end of the lever is loosely attached to the rubber diaphragm which forms the bottom of the pump housing and the diaphragm is pulled down.
- As the lever lowers the diaphragm, it creates a suction and draws fuel into the pump via a one-way valve along the fuel line.
- With more rotation of the turntable, it no longer presses the lever and the lever returns to the return spring, thus loosening to pull the diaphragm.
- The loose connection lever does not lift the diaphragm, but a return spring moves it. • The diaphragm can only be moved upward by expelling the fuel from the chamber. Fuel cannot be returned through the first one-way valve, so it flows to the carburetor through another one-way valve.
- The carburetor injects fuel into its buoyancy chamber only when needed through a needle valve.
How Electric fuel Pump work?
- An electric diaphragm pump has the same arrangement as the valves, but instead of a camshaft, a solenoid provides the diaphragm pulling force.
- The solenoid valve pulls a steel rod, lowers the diaphragm, and draws fuel into the chamber.
- At the end of the movement, the iron rod separates a series of contacts, which separates the current from the electromagnet and reduces the diaphragm voltage.
- When the diaphragm return spring raises the diaphragm, it also moves the stem away from the contact and then closes them so that the solenoid valve lowers the stem and diaphragm again.
Three common causes of fuel pump failure are:
- Fuel Pollution – Fuel is damaged by corrosion, waste, and moisture, which carry visible pollutants into the fuel tank.
- Filter/filter block: The pollutants mentioned above block major components including filters, filters, and the fuel pump itself. This blockage affects fuel flow, which can affect the vehicle during acceleration and other long-term damage.
Electrical Problems – Electrical failures are also a major cause of fuel pump failure.
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