Engine Fuel Feed System:
The main purpose of the fuel feed system is to control the fuel supply to the engine. To supply the fuel from the fuel tank to the engine cylinders, manufacturers use the following methods in case of a petrol engine.
Types of Fuel Feed systems of a petrol engine:
- Gravity Feed
- Pressurized Feed
- Vacuum system
- Pump Feed
- Fuel injection system
First four out of these fuel feed systems work with carburetor while the fuel injection system uses an injector to supply the fuel to the engine cylinders.
Gravity Feed System:
The ‘gravity system’ is confined to smaller vehicles such as entry-level two-wheelers, bikes, and quads only. In this design, the engineers mount the fuel tank at the highest position. It feeds the fuel into the carburetor float chamber by gravity. This system has a very simple design and hence, cheaper to produce and maintain. However, the disadvantage is that you need to place the fuel tank over the carburetor for this system to work correctly.
Pressure Feed system:
The pressure feed system uses a hermetically sealed (airtight) fuel tank. In this design, a separate air pump or engine exhaust creates pressure in the tank. However, for starting the engine; you need to hand prime the pump. Thus, it creates pressure and forces the fuel to flow to the carburetor. Although there are chances of leaking of pressure, you can place the fuel tank at any suitable location in the vehicle which is an advantage.
This system uses engine suction pressure to suck the fuel from the main tank to an auxiliary tank. From there, the fuel flows to the carburetor float chamber by gravity. This system is now obsolete.
Pump Feed System:
Most present-day cars use this system. This system uses a steel pipe to supply the petrol to the fuel pump which then pumps it into the carburetor float chamber thru’ flexible pipe. If it is a mechanical fuel pump, then it gets the drive from the engine camshaft. Hence, it is attached to the engine. On the other hand, electrically operated fuel pumps can be placed anywhere. So, manufacturers place it inside the fuel tank to reduce the chance of vapor-lock.
Fuel Injection System:
Modern/present-day vehicles use petrol injection system which replaced the carburetor. The injector nozzle atomizes the fuel and forces it into the air stream. Newer generation engines use separate injector for each cylinder. The air-fuel mixture for different load and speed conditions is controlled either mechanically or electronically. Hence, this makes the fuel system more accurate. For more information, read about the EFI, MPFI & GDi.
The petrol engine fuel system consists of the following parts:
- Fuel tank
- Fuel pump
- Fuel lines
- Carburetor or injectors
- Engine-management system
- Fuel gauge
Bosch and Delphi are some of the leading manufacturers and suppliers of the engine fuel feed systems in the world.
The fuel feed system for Diesel engines is slightly different than that used for the petrol engines. It carries out the following functions which are –
- Storing the diesel fuel.
- Filtering the diesel.
- Delivery of the fuel to Fuel Injection Pump. – DI, IDI or CRDi etc.
- Injecting the fuel into the engine cylinders.
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