What is Fuel System?
The fuel system consists of the fuel tank, pump, filter, and injection nozzles or carburetor and is responsible for supplying fuel to the engine as needed. Every component must function properly in order to achieve the expected vehicle performance and reliability.
The function of the fuel system is to store fuel and deliver it to the cylinder chamber where it can be mixed with air, vaporized, and burned to produce power. The fuel, which can be either gasoline or diesel, is stored in a fuel tank. A fuel pump draws fuel from the tank through fuel lines and pumps it through a fuel filter to either a carburetor or fuel injector and then into the cylinder chamber for combustion.
How Does My Car’s Fuel System Work?
Ideally, when your vehicle’s gas gauge gets down to a quarter tank, you’ll drive to your favorite gas station and fill up the tank. The fuel begins its journey at the pump:
- From the pump to the tanks, the gas flows through the fuel pump. The pump delivers fuel from the gas tank to the engine. Some vehicles are equipped with multiple gas tanks and even multiple fuel pumps. Multiple fuel pumps are ideal for ensuring the vehicle always has access to fuel regardless of the terrain it is traveling on. For example, when a vehicle is making a sharp turn or driving up a steep grade and gravity pushes fuel away from a fuel pump, it guarantees that at least one of the pumps has access to fuel.
- The pump forces fuel through the fuel lines, which deliver fuel from the tank to the engine for combustion. Fuel lines are made of durable metal and plastic materials, and while they’re under the vehicle’s floor and seemingly in a vulnerable spot, they’re placed in areas that can’t be damaged by weather, road conditions, or heat exposure to the engine’s exhaust or other components.
- The fuel filter is the next stop for gasoline before it reaches your engine. It is imperative that the fuel entering the engine be clean and free of dirt or particles. To prevent debris from entering the engine, the fuel filter helps remove dirt or debris. A clogged or dirty fuel filter cannot prevent harmful particles from entering your engine and causing all kinds of damage. Newer vehicles may not have serviceable fuel filters since they are located in the fuel tank. Replacing the filter requires replacing the entire assembly.
- Once the fuel has passed the fuel filter, it reaches the engine and is injected into the combustion chamber to create combustion using fuel injectors.
Parts of a Fuel System in a Car
The car fuel system is comprised of several different components to make this entire process happen smoothly. There is a fuel pump, fuel tank, fuel lines, fuel filter, fuel injectors, and carburetor. It is really no different than the heart, veins, and kidneys of your body working together to keep you moving.
If just one of these components were to malfunction, it could interfere with the entire fuel transferring process. Then your engine would either not function at all, or it would function very slowly. Below is a list of the components of a car fuel system.
- Fuel Pump: Inside the fuel tank is a component called the fuel pump. Many newer cars have the pump in the tank. If you have an older vehicle, you may find the fuel pump in the center of the engine and fuel tank. It can also be connected directly to the motor. The job of the fuel pump is to pump fuel into the engine. You probably have an electric pump that is powered by the car battery if the pump is in the fuel tank. Otherwise, the movement of the motor drives the pump when it is outside.
- Fuel Tank: The fuel tank should be self-explanatory. When you pump fuel into your vehicle, fuel goes into your fuel tank. This is where your fuel is stored before being pumped into the combustion chamber. You may also find the fuel pump and exhaust technology inside.
- Fuel Filter: The engine must have clean fuel to function properly and run smoothly. The fuel filter is usually positioned around the fuel pump, either before or after it. When the fuel is pumped out of the fuel tank, all the tiny particles and impurities it contains are blocked by the filter before the fuel enters the engine.
- Fuel Injectors: The fuel injectors of modern vehicles are controlled by electrical sensors and computers. Whenever you step on the gas or push the engine harder, a small electric valve is signaled to open and allow fuel into the internal combustion chamber. When the request is complete, the valve is signaled to close. This valve is basically the vehicle’s fuel injector.
- Carburetor (older cars): As you know, the internal combustion engine requires a mixture of air and fuel before ignition. On older non-fuel injected cars, a carburetor is the component responsible for mixing the fuel and air. After the mixture has taken place, it is sent to the combustion chamber, where the spark plug ignites it.
- Fuel Lines: There are all types of fuel lines in the fuel system. Fuel lines allow fuel to flow from one component to another. For example, they transport the fuel from the fuel tank to the carburetor.
Different Types of Fuel Injection Systems in Cars
Broadly speaking, there are 4 different types of fuel injection systems in cars
- Single-point or throttle body injection
- Port or multipoint fuel injection
- Sequential fuel injection
- Direct injection
1. Single-Point or Throttle-Body Injection
This is the most basic type of fuel injection system. Also called the Throttle-Body injection system, the single-point system replaced the carburetor with up to two fuel injectors in the throttle body. For the uninitiated, the throttle body acts as the starting point of the respiratory system of a car’s engine as it’s at the starting of the air intake manifold.
The single-point fuel injection system worked well as a replacement for rudimentary carburetors before multi-point fuel injection systems came into existence. While these were not as precise as the multi-point units, they did offer better efficiency than carburetors. Also, they even required lower maintenance and were even easier to service.
2. Port or Multipoint Fuel Injection
A common type of fuel injection system these days is the Multipoint Fuel Injection System which offers a separate injector nozzle for every cylinder. It’s placed on the outside of each intake port, and this is exactly why it’s also called a port injection system at times.
Having the fuel vapor near the intake port makes sure that it will be completely sucked into the cylinder and enhance combustion. The biggest advantage of the MPFI system is that it regulates fuel in a more efficient way as compared to carburetors or single-point fuel injection. Also, this system mitigates the possibility of fuel condensation in the intake manifold.
3. Sequential Fuel Injection
A sequential fuel injection system is also known as a sequential port fuel injection system (SPFI) or even a timed injection system. The biggest difference between multi-point fuel injection and sequential fuel injection is that in the former, all the injectors spray the fuel at the same time, which means the fuel often remains in a port for more than 150 milliseconds when the motor is idling.
While it might not sound like much time, it’s actually more than enough time to decrease efficiency. In a sequential fuel injection system, each nozzle sprays fuel independently. Basically, they spray the fuel just before the intake valve opens, which means the fuel doesn’t have to hang around for long. As a result, the efficiency improves, and emissions get lower.
4. Direct Injection
Direction injection is easily the most advanced type of fuel injection system. In this system, fuel is directly sprayed into the combustion chambers after the valves. This system is mostly found in Diesel engines, but of late, it has also started making it to mainstream petrol motors.
For example, the 1.0-liter turbo-petrol motor of the Hyundai Venue gets direct injection and is marketed as ‘GDI.’ In this arrangement, the regulation of fuel and the timing of spraying it is even better measured than in any other injection system.