Fuel pump vs fuel injector. What are the differences?

Most motorists cannot tell the difference between a fuel pump and a fuel injector. These two devices have few similarities and many differences.

The main difference between these two components is that the fuel injector atomizes the pressurized fuel and injects it into the combustion chamber while fuel pumps pressurize fuel and then send it to the fuel line and fuel injectors.

In this article, we will review these two crucial components of the car to help you understand both their similarities and differences. Now, without further ado, let’s dive into the article.

What is a fuel pump?

As its name suggests, a fuel pump is a device that draws petrol out of the tank via a pipe to the fuel injector of the internal combustion engine.

This device is an important part of the internal combustion engine because it supplies fuel to keep the engine running. The engine requires a steady and stable supply of fuel delivery and that is exactly what the fuel pump does.

This component operates by creating higher pressure in the fuel lines, pushing the fuel to the engine.

Fuel pressure needs to be within certain limits for the engine to run efficiently. If the gasoline pressure is too high, then the engine will be rich and rough, meaning it will not run all fuel being pumped in, making the engine inefficient.

On the other hand, if the fuel pressure is too low, then the engine may misfire, stall or run lean. The fuel pump plays a crucial role in ensuring that the engine receives the right amount of fuel to function optimally.

What is a fuel injector?

Fuel injectors are electronically controlled valves that are supplied with pressurized fuel by the fuel pump. When fuel injectors are energized, they atomize the fuel into a fine mist for easy and even burning in the combustion chamber.

For the engine to run efficiently and smoothly, it needs to be provided with the right mixture of fuel and air and that is exactly what a fuel injector does. They are usually placed at a certain angle to inject the right amount of fuel into the engine.

What is the difference between a fuel pump and a fuel injector?

Now that we have defined these two components, the next question in your mind is how the two differ from each other. Below is a summary of the differences between these two components

Fuel pumpFuel Injector
It transports fuel from the tank through a pipe to the combustion chamberThey atomize the pressurized fuel as well as inject it into the combustion chamber
It is located in the fuel tankIt is located  on the engines intake side  under the fuel rail
It increases pressure  within the fuel systemIt decreases the pressure within the fuel system
It is 5-7 inches long with a diameter of 4-5 inchesIt is 3-5 inches long  with a diameter of 1-2 inches


  • Both fuel injectors and fuel pumps are powered by the car’s electrical system
  • They both supply fuel for the car’s engine
  • They both supply fuel at varying intervals

Both the fuel pump and fuel injectors are crucial components of the car when it comes to ensuring the engine gets the right amount of fuel on time.

However, how they function differs greatly. The main role of the fuel pump is to supply fuel via the pipe to the combustion chamber.

Fuel injectors, on the other hand, atomize the pressurized fuel and inject it into the combustion chamber, thus ensuring the engine runs smoothly and efficiently.

Are fuel injectors in the fuel pump?

NO, fuel injectors are not in the fuel pump. They are located on the engine’s intake side under the fuel rail. On the other hand, the fuel pump is located in the fuel tank.

How do you know if it is your fuel pump bad or fuel injector problem?

Just like other components in the car, the fuel pump and the fuel injector can break down. So, how do you know if the problem is on the fuel pump or the fuel injector? In this section, we will tell how to detect which of these two components has a problem.

Symptoms of a bad fuel pump

Fuel tank noise

When your fuel pump is damaged, you will hear a loud whining noise coming from the fuel tank, especially when you are low on fuel.

Difficult starts

If your fuel pump is failing, it will not be able to get fuel to the engine on time, resulting in difficult starts.

Power loss

A bad fuel pump will result in your car losing power, especially when driving uphill when it is loaded, and when you drive at faster speeds.

Low fuel efficiency

Your car will consume more fuel than it used to because the fuel pump is pumping too much fuel to the engine.

Sputtering engine

If your fuel pump is bad, it will not be able to supply a constant stream of fuel to the engine causing your engine to sputter, especially when driving at higher speeds.


If the fuel pump has broken down completely, your car will stall. The engine can only operate if it gets a steady supply of fuel.

Check out here a detailed article about fuel problems symptoms and problems.

Symptoms of a Bad fuel injector

Engine misfire

A faulty fuel injector may cause the engine to misfire because it does not get a steady supply of gasoline.

Rough idle or the engine stall

A bad fuel injector may also cause rough idle or stalling of the engine because of a sudden drop of fuel.

Bad fuel economy

Faulty fuel injectors may supply too much fuel to the combustion chamber, leading to bad fuel economy.

Both the fuel pump and fuel injectors share many symptoms. So, the best thing to do is take your car to the mechanic for a checkup if it is showing any of the above-listed symptoms to determine which component between these two is faulty.

Final thoughts

If you have been wondering how the fuel pump and fuel injectors differ we hope that this article has been of help. Although both components supply fuel to the engine, the fuel pump draws fuel from the pump via pipes to the engine while fuel injectors atomize the fuel into a fine mist for easy and even burning in the combustion chamber.

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