If your car’s fuel system fails, you’ll be in trouble. But you really don’t want to run out of fuel before that! A car’s fuel system is crucial for the functioning of the combustion engine and runs from the fuel tank to the engine.
To ensure the engine gets the proper air-to-fuel ratio with fuel included, the fuel must travel from the tank to the engine. What happens if the fuel system or the engine stops moving due to various issues that can occur?
Find out how the fuel system works to be able to continue moving and how to service the fuel system to ensure your vehicle has the fuel necessary to keep moving.
What is a Fuel System?
A fuel system is made up of a fuel tank, a fuel pump, fuel filters, and fuel injectors (or carburetor) to transfer fuel to an engine when needed. All parts of the fuel system must function perfectly together to give us the expected performance and reliability of the vehicle.
The fuel system works by keeping fuel in the fuel tank and sending it to the combustion chamber, where fuel can be mixed with air, vaporized, and burned to produce power. Fuel stored in the fuel tank is in either gasoline or diesel form.
The fuel system operates a fuel pump to pull fuel out of the fuel tank, which is all connected by fuel lines. The action of the fuel pump is to pump fuel from the fuel tank through a fuel filter either to a carburetor (or fuel injectors) to later be sent to the combustion chamber for combustion.
Parts of a Fuel System in a Car
A car’s fuel system has several components designed to make the delivery of fuel seamless. Components include a fuel pump, fuel tank, fuel lines, fuel filter, fuel injectors, and carburetor. It is not much different from the heart, veins, and kidneys functioning together in your body to keep you moving.
If one of those components fails, it will inhibit the fuel transfer process altogether. Thus, your engine is either unable to function or functions slowly. Below is a list of components of a car’s fuel system.
1. Fuel Tank.
The fuel tank is where the fun begins. The most straightforward function of the fuel tank is to simply store gasoline until it is ready to be used. However, there is more going on with the fuel tank than that. Inside the tank, it has a sending unit that lets you know how much gas is in the tank.
The sending unit is typically a float on a metal arm that is connected to a resistor. It sends a signal to the instrument cluster in your vehicle that lets you know how much gas you have.
#2. Fuel Pump.
When you turn on your ignition, the fuel pump pumps gas from the gas tank. If you have an older vehicle, it probably has a mechanical pump on the exterior of the gas tank. If you have a newer vehicle, it most likely has an electric fuel pump, and it is always in the tank.
The new electric pumps are more fuel-efficient than the mechanical or centrifugal pumps found on older vehicles, especially with today’s concern over fuel efficiency in high-compression, modern vehicles.
If you need a replacement, the Cummins fuel pump is one of the most robust and reliable options on the market, proven time and time again to deliver fuel reliably and with improved performance.
#3. Fuel Filter.
Fuel filters remove contaminants present in fuel before they reach the engine, such as dirt, rust, or any other unwanted particles that could ruin your engine. Fuel filters can be located in the fuel tank or in the fuel lines.
#4. Fuel Lines & Fuel Rail.
The fuel has been pumped out of the tank and filtered, and now it is on its way to the engine. Fuel is transported through the fuel lines, made of either metal or reinforced rubber to transport gasoline from the tank to the engine.
At the end of the fuel line, the fuel connects to a fuel rail, where we will encounter the next and last components of the system.
#5. Fuel Injectors/Carburetors.
Before the fuel goes to the combustion chamber in the engine, it finally stops at the fuel injector. In short, the fuel injector is an electrically operated gate that opens just enough and just long enough to allow the right amount of gasoline to make your car run.
Most combustion engines were not capable of using any electronic device until the late 1980s, so gasoline was delivered through a carburetor. Carburetors are not an electrical device, but are mechanical devices that just mix vaporized fuel and air to make a combustible fuel or vapor for combustion engines, and have been mostly replaced by electronic fuel injectors.
How A Car’s Fuel System Works?
The fuel system consists of a fuel tank, fuel pump, fuel filter, and fuel injectors.
When you visit a gas station to fill up your vehicle, that is only the initial step in the combustion process of your fuel. Your vehicle’s fuel system allows itself to make the power required to move your vehicle.
The sequence of steps for how fuel really gets into the engine is a 4-step process.
- After placing the nozzle in the fuel filler inlet tube and filling the fuel tank, the moment you drive away, the fuel pump sends the gas through the fuel lines to the engine.
- The fuel lines are made of durable metal and special plastics that are located under the vehicle and out of exposure to wear and tear from the road environment, heat, or element exposure. The fuel will be at one more stop before reaching the engine.
- To prevent debris and contaminants from damaging the engine, the fuel must go through the fuel filter. Because the fuel filter’s job is to trap dirty fuel or debris at anything after about 60,000 miles, but being clogged could lead to some unfortunate results. If it is simply clogged, the fuel filter may not be able to pass cleaner fuel prior to the fuel reaching any part of the engine. To note: Not to digress, but more often than not, the fuel filter is part of the fuel pump, and unfortunately, most modern vehicles do not allow filtering of fuel.
- Finally, if the fuel passes through the filter properly, the fuel will reach the engine and will be injected into the combustion chamber by means of a fuel injector or fuel injectors.
What is a Car’s Fuel Injection System?
Depending on the age of the vehicle, your car contains one of four options that help deliver fuel to the engine, for the combustion process: a carburetor, mechanical fuel injection, direct fuel injection, or electronic fuel injection.
#1. Carburetors.
Carburetors create suction, which draws in air, by creating pressure in the engine. Unfortunately, carburetors are limited in their efficiency due to the fact that they do not adapt to varying RPMs.
The difficulty with carburetors derives from the throttle determining how much air and fuel are necessary at a given moment based on the speed of the vehicle, thus changing the flow ratio, for air versus fuel, potentially utilizing too much fuel and compromising performance.
#2. Mechanical Fuel Injection.
Mechanical fuel systems initially utilized a fuel pump that injected high spurts of fuel into the injector for each cylinder. Upon delivery of fuel to the injector, the pressure would open the injector and spray that atomized fuel into the intake of the combustion chamber.
Mechanical fuel injection utilized pistons driven by camshafts to create the input of fuel, yet adjustments were limited to achieve a correct ratio of fuel to air. Instead, the ratio produced was only viable for the weight or capability of the engine.
Later, mechanical systems utilized fuel distributors to more accurately gauge flow rate based on the insumption of air into the engine.
#3. Direct Fuel Injection.
Diesel vehicles mostly use direct fuel injection. It is one of the most efficient ways to use fuel. The fuel is injected directly into the cylinder in the combustion chamber. In diesel direct injection, the fuel is able to burn at the necessary moment and right where it needs to.
The fuel can burn better and improve fuel economy due to the leaner fuel-to-air mixture and the way the fuel is introduced into the chamber.
#4. Electronic Fuel Injection.
This is what most vehicles use today, which is a more advanced and computerized control mechanism that ensures fuel economy and performance.
The fuel pressure regulator allows a specific amount of fuel through the injectors in predetermined increments based on calculations that come from the Mass Air Flow sensor, which detects how much air enters the engine.
This action of allowing a predetermined amount of fuel to be injected at a time allows the vehicle’s computer to determine the full amount of fuel for the fuel system to operate in an efficient manner.
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.
A single-point injection system has a common fuel injector for all the cylinders in the combustion chamber of the engine. It is the oldest and one of the simplest types of fuel injection systems.
Instead of a carburettor, in a single-point injection system, one or two fuel injector nozzles in place of the carburettor in the throttle body, and that’s why it is also called Throttle body injection (TBI).
The fuel will be sprayed in all cylinders simultaneously; however, as opposed to the carburettor jet, it is from an injector, and it can be monitored electronically by an electronically controlled unit (ECU).
Compared to carburettors, there is, of course, some improvement, although, because there is a single injector, it does have a slight disadvantage that, at a higher RPM, the use of a single injector disturbs the performance of an engine and may cause a slightly rough ride quality to occur as the required fuel supply is not met.
Additionally, a small portion of the fuel does not get burned up in the cylinders, and it condenses outside of the intake manifold, which is a waste of fuel.
2. Port or Multipoint Fuel Injection.
With multi-point fuel injection (MPFI) technology, each cylinder in the combustion chamber has an injector at the front of its inlet valves (outside the intake port), which is also why they call it ‘Port Injection’.
With MPFI, the injectors spray fuel at the same time, and every cylinder receives a more precise volume of fuel with less potential for fuel condensation outside the intake manifold.
While MPFI has the advantage of lower fuel wastage than TBI, the fuel spray occurs in time synchronously in every cylinder; this means the fuel pools in the engine and port for a longer period, potentially up to 150 milliseconds.
From a performance standpoint, MPFIs perform better than TBIs.
3. Sequential Fuel Injection.
The sequential fuel injection system solves the only disadvantage of MPFI, and is the most popular fuel injection system in use today. In a sequential fuel injection system, the fuel injectors operate relative to their connected cylinders.
Each injector sprays, or injects, fuel only when the intake valve of the cylinder is opened, and the injector is idle during the other steps. The ECU observes the motion of the cylinders and actuates the injectors only when needed.
The sequential fuel injection is the most efficient and effective of all the fuel injection systems currently being utilized in the automotive industry.
4. Direct Injection.
Direct fuel injection concentrates on putting the injector in the cylinder and injecting the fuel directly into the cylinder, without the intake valve or manifold.
While this injection system is generally for diesel engines, it has an important spot in petrol engines called GDI (gasoline direct injection).
In these systems, the fuel is sprayed on the intake and there is always the possibility of fuel condensation to some extent. In the DI system, all the fuel is injected directly into the cylinder, resulting in maximum fuel economy, and that is the biggest advantage of the DI system.
Direct injection has been part of diesel engines since the 1920s, and for petrol engines since World War II. Car manufacturers have also learned that GDI engines are more powerful and more practical for better CNG fuel efficiency.
What Is Included in a Car’s Fuel System Service?
Fuel is critical for vehicle operation. To avoid failure of fuel components, especially the fuel pump, it is important to maintain your fuel system. If any fuel components fail, your car will not run or will be difficult to run.
To avoid issues, never let the vehicle’s fuel level drop below a quarter of a tank, replace the fuel filter, and have fresh fuel system cleaner installed regularly.
Change your fuel filter every 60,000 miles and have a fuel system cleaning every 30,000 miles. This will minimize the likelihood of being stranded with bad fuel injectors, a dirty fuel filter, or a failed fuel pump.