What is a Fuel System? – Components, and Working

The fuel system in a vehicle consists of a few components that help transfer fuel from the tank to the engine for combustion.

Since fuel delivery to the engine is essential for smooth driving; your fuel system must always be in efficient working condition. If there is a lapse in the system you will feel a loss in power and performance.

Let’s take a look at the components in a fuel system in detail to get a better understanding of how the fuel system works and how each component plays a part in the fuel system.

What is a 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?

How fuel moves through a car:

1. It Starts with the Fuel Pump

If you want to be technical, it starts at the tank when you remove the gas cap and pump fuel in. From here, both gasoline and diesel fuel are picked up by the fuel pump, where the real action begins.

The vast majority of vehicles today have a fuel pump that resides in the fuel tank itself. If it doesn’t, it’s located on the frame or subframe, which is far less common.

On a standard electronic fuel injected vehicle, which still makes up a vast majority of vehicles on the road, this pump then provides the volume, and pressure of the fuel.

Older, carbureted vehicles generally have a suction-style fuel pump that is mounted to the engine, and draws the fuel out of the tank, into the pump, and pressurizes it on its way to the carburetor.

The newest technology for gasoline engines is direct injection, which requires in most cases 2 fuel pumps – a “lift” or “transfer” pump which pumps fuel up and out of the fuel tank, and then a pressure pump, usually mounted on the frame or subframe of the vehicle, which then provides fuel to the injectors at high pressure.

This is very similar to how a Diesel engine works, where the lift pump in the tank supplies fuel usually to a mechanical, high-pressure pump mounted on the engine.

2. It travels through Fuel Lines and Filters

If the fuel pump does what’s expected of it and draws the fuel from the tank, this fuel first has to travel through metal or plastic fuel lines, which run from the tank to the engine.

The fuel filter then actively filters this fuel to remove micro-debris, whether it’s fasoline or diesel.

3. The Fuel Pressure Regulator

All fuel systems have an optimum pressure they have to run at. On older carbureted engines, this pressure is low – between 3-5PSI. On multi-port Electronic Fuel injection systems, it’s much higher – usually between 50-90PSI.

Each system will have a regulator that takes the fuel pressure from the pump, and regulates it to the proper volume, and pressure. While fuel pressure regulators don’t commonly fail, they can, and when they do, issues with performance or no-start/no-run situations can happen.

On most Diesel engines, the injection pump, or pressure pump, also controls the pressure.

4. Next Stop, the Engine

After the filter has removed any contaminants and the pressure regulated properly, it is time for the fuel to go to the engine where it can finally be of use.

There are a few different ways the fuel can go into the engine. Which way your car does it is likely a matter of when your car was built.

Carburetors were the norm of getting fuel to the engine for half a century. The carb had a float that would raise and lower to allow gas to enter the engine at different rates, depending on how open the float was.

Fuel injectors handle supplying fuel to almost all modern engines. These devices can be either mechanical or electronic, whereas modern systems, either Direct-Injection or Multi-port/Sequential are all electronic.

Electronic fuel injectors are controlled by the ECU, and can inject fuel with far greater precision than a purely mechanical carburetor because the ECU has total control.

Once the fuel is in the engine, it can be combusted and expelled through the vehicle’s exhaust system.

Parts of a Fuel System

The fuel system is made up of the fuel tank, pump, filter and injectors or carburetor, and is responsible for delivering fuel to the engine as needed. Each component must perform flawlessly to achieve expected vehicle performance and reliability.

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.

#1. 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.

#2. 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.

#3. Fuel Filter.

The fuel filter is the key to a properly functioning fuel delivery system. This is more true with fuel injection than with carbureted cars.

Fuel injectors are more susceptible to damage from dirt because of their close tolerances, but also fuel-injected cars use electric fuel pumps.

When the filter clogs, the electric fuel pump works so hard to push past the filter, that it burns itself up. Most cars use two filters.

One inside the gas tank and one in a line to the fuel injectors or carburetor. Unless some severe and unusual condition occurs to cause a large amount of dirt to enter the gas tank, it is only necessary to replace the filter in the line.

#4. Fuel Lines.

Steel lines and flexible hoses carry the fuel from the tank to the engine. When servicing or replacing the steel lines, copper or aluminum must never be used. Steel lines must be replaced with steel.

When replacing flexible rubber hoses, proper hose must be used. Ordinary rubber such as used in vacuum or water hose will soften and deteriorate. Be careful to route all hoses away from the exhaust system.

#5. Fuel Injectors/Carburetors.

The fuel injector is the last stop for fuel in your engine before it goes “boom!” inside the combustion chamber. It is basically an electrically operated gate that opens just long enough to meter the perfect amount of fuel to run the engine.

Carburetors were the usual method of fuel delivery for most vehicles up until the late-1980s.

Most carburetors are manual non-electric devices that are used for mixing vaporized fuel with air to produce a combustible or explosive mixture for internal combustion engines.

Carburetors have been mostly supplanted by electronic fuel injection.

#6. Intake Valve.

The valve opens to allow the air/fuel mixture to be drawn into the combustion chamber. Deposits on the intake valves can restrict or change the flow of the air/fuel mixture into the combustion chamber.

Fuel can stick to deposits on the intake valve and not enter the combustion chamber when needed. The right fuel additive can help reverse these effects and restore lost performance.

#7. Piston.

The piston travels up and down and converts the pressure from combustion into movement.

Detergent additives that can help remove or reduce deposits have been shown to be effective in reducing or eliminating deposit-related drivability and performance loss.

#8. Combustion Chamber.

This is where the burning of the air/fuel mixture happens. Deposits in the combustion chamber can affect heat transfer and air/fuel compression. Excess heat can cause premature ignition and knocking.

Some vehicles contain knock sensors that are used to determine engine knock or pre- or post-detonation. With these sensors, the computer will detune the engine to eliminate this symptom, which has an adverse effect on performance.

Fuel system deposits will cause knocking, which is why it is so important to keep your fuel system clean.

What Clogs The Fuel System?

 Fuel, oddly enough. Fuel varnish deposits are usually what gets in the way of that perfect cone of fine droplets.

If you’re noticing:

• A loss in power
• Lower gas mileage
• Hesitation when you put your foot down

It may be time for a fuel system cleaning. It takes 3 separate steps to get your fuel system really clean.

• Clean the gas pump, fuel lines and injectors by adding cleaner to the gas and running the engine.
• Add a second cleaner directly to the warm engine to remove gunk and carbon deposits from the combustion chambers.
• Finally, hand-clean the air intake using a third cleaner and bottle brushes to remove rough deposits that disturb air flow and cut efficiency.

What Is A Fuel System Cleaning?

Every gas-powered vehicle has pipes that take the fuel from the gas tank to the engine. Fuel filters help prevent blockage from dirt, debris, and other materials. The fuel injector is the most commonly blocked component.

The spark plugs won’t burn the gasoline and power the vehicle forward when this happens. Cleaning this system can correct these problems.

#1. Identifying Problems With the System.

When your vehicle’s fuel system starts to experience problems, you will quickly notice it. Components such as the sensors can start to falter or wear down. To prevent more significant problems, pay attention to the warning signs.

These include rough engine starting, shuddering while the car is idling, and losing power when driving uphill or downhill.

The engine may accelerate or respond slowly when you press the gas pedal. If you notice any of these issues, bring your car to the technicians for vital maintenance.

#2. Clean the Injectors.

Fuel gets to the engine via the fuel injectors, which spray the fuel as a mist. Any debris in the fuel system can clog the injectors and prevent this essential process from occurring.

A technician will remove any build-up on the injectors and clean them thoroughly. If you notice any of these issues, bring your car to the technicians for vital maintenance.

#3. Remove Fuel Varnish From the Throttle Body.

The fuel throttle can stick, hampering its ability to control the air intake. The throttle could also become stuck in the open positions due to the buildup of deposits.

Thus, cleaning the throttle of the fuel system gets rid of any fuel varnish and allows air to flow freely. A technician will check to ensure that the throttle and sensors work properly.

#4. Change the Fuel Filter.

When you get an oil change for your vehicle, technicians often check the air filter during these visits. Similarly, the fuel filter needs replacements as well. As time goes by and the mileage piles up on your car, the filter will become dirty.

A dirty filter will fail to keep debris out of your vehicle and fuel system effectively. Check your vehicle’s owner’s manual to see how often you should replace the filter.

What Is Fuel Injection?

Fuel Injection is the process of introducing fuel into an internal combustion engine.

Diesel (compression-ignition) and petrol (spark-ignition) engines have their fuel injection systems, providing portion fuel injection through small nozzles under high pressure in the combustion chamber.

In the beginning, manufacturers used fuel injection systems in aviation to help pilots run the engine in any plane position.

The first mass-produced diesel passenger cars with fuel injection appeared in the late 1930s. Early injection systems were inefficient, so they were quickly overtaken by carburetor motors.

A fuel injection system is a critical component in modern IC engines, responsible for precisely delivering fuel to the engine’s combustion chamber. Unlike older carburettor systems, they offer superior control over the fuel-air mixture, resulting in improved engine performance, fuel efficiency, and reduced emissions.

These systems use electronic sensors and injectors to precisely meter and atomise the fuel, ensuring that the engine runs smoothly under various conditions.

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 get s 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.

FAQs.