Informational Guide

How Does A Fuel Pump Work?

We look at the different types of fuel pumps and how they work. This guide also shows you how to maintain your fuel pump for reliable operation.

Your car's fuel pump is an essential component of the fuel injection system. How does a fuel pump work?

We look at the different types of fuel pumps and how it works. This guide also shows you how to maintain your fuel pump for reliable operation.

Mechanical Fuel Pump

How does a mechanical fuel pump work? It is driven by the camshafts. With each turn of the camshaft, the cam moves under the pivoted lever, forcing it up at one of the ends.

On the other lever end, there is a rubber diaphragm that goes down. When the lever pulls this diaphragm down, suction is produced that pulls fuel into the pipe and through a one-way valve. These fuel pumps are found on many older vehicles, but nothing from the past few decades.

Electric Fuel pump

The electric pump works in a similar fashion, but it doesn't rely on the camshaft. Instead, it uses a solenoid to pull the diaphragm down and create suction. The electric fuel pump is used on all modern vehicles.

Vacuum Fuel Pump

How does a vacuum fuel pump work? You might notice these on some scooters and motorcycles, but how does a motorcycle fuel pump work? It runs with the vacuum of the compression coming from the motor. This vacuum operates the diaphragm inside the fuel pump to circulate fuel.

Pulse Fuel Pump

How does a pulse fuel pump work? This type of pump contains four tubes. One runs to the fuel tank, while two connect each carburetor, and the final tube is connected to the crankcase. As the engine revolves, the tube that connects to the engine pumps fuel from the pressure of those revolutions.

How Does a Fuel Pump Work?

On your vehicle, the fuel tank and engine are usually kept separate to ensure safety. So, how does the necessary fuel get to the engine?

With the help of a fuel pump. Gas is pumped from a pipe in the tank to the engine. Fuel injection systems push the gas until it is mixed with air in the inlet manifold.

car fuel system

Fuel pumps can be either mechanical or electric, which changes the location of it. Some are next to the fuel tank, while others are located inside the tank itself.

These systems only pump fuel when the engine needs it, with systems in place to stop the flow when gas isn't needed.

How Does a Diesel Fuel Injection Pump Work?

Common rail fuel injection pump

This electric fuel pump is found on the newest models and includes the supply pump, electronically controlled injectors, sensors, plus a common rail. The engine operates the supply pump to create high-pressure fuel delivery that is distributed by the common rail to the injectors.

Distributor (rotary) fuel injection pump

This electronic pump runs with an actuator, electronic control unit and sensors. It works similar to the common rail pump, but the actuator controls the amount of fuel that's injected.

In-line fuel injection pump

This mechanical pump utilizes the camshaft to drive fuel pressure and injection through the pump body. Fuel is fed to each cylinder.

Distributor injection pump

This mechanical fuel pump has one fuel pressure mechanism instead of one for each cylinder. The distributor follows the proper injection order to supply pressurized fuel to the cylinders. How does a small engine fuel pump work? If it is a diesel motor, this is the perfect setup.

Tips for Maintaining Your Fuel Pumps: Mechanic’s Advice

While maintaining a fuel pump isn't something that's part of a regular tune-up, there are some steps you can take to make it last longer.

  • Only use top tier gas in the fuel system.
  • Keep your gas tank filled halfway or more to ensure the pump motor doesn't overheat.
  • Don't get fuel if the station is getting filled up. Dirt and contaminants get stirred up during this process, making their way into your fuel system.
  • Change the fuel filter regularly, according to the manufacturer's recommendations.
  • Add an anti-ethanol agent (gas engines only) if you don't use a tank in two weeks to keep it from jelling.

People Also Ask (FAQs)

What are some benefits of high pressure fuel pumps?

The high-pressure fuel pump creates better fuel efficiency, is safer to run, and cheaper in the long run.

How do I know that my fuel pump is failing?

A bad fuel pump starts making a whining noise. It can also cause trouble starting the engine or create a sputtering sensation while driving. You might have a bad fuel pump if the engine stalls at high temperatures, feels like it loses power during acceleration, or starts surging. You might also start getting worse fuel economy because of the failure.

How does a fuel pump work on a small engine?

Many smaller engines rely on vacuum power to move the fuel through the system.

Why would a fuel pump not get power?

If there's an electrical system issue, such as a defect with wires, a switch or the circuit, your fuel pump might not get the power it needs.

How long do fuel pumps last?

Fuel pumps are made to last as long as you take care of them. When properly maintained, a fuel pump can last 100,000 miles or more.

Can a fuel pump go out without warning?

Many fuel pump problems occur without warning. One day you will be driving without any issue and the next day, the car might not start anymore.

Can you drive with a faulty fuel pump?

When the fuel pump starts to go, your engine doesn't receive the power it needs to keep going. Because of this defect, the car could leave you stranded at any moment and shouldn't be driven.

What does a bad fuel pump sound like?

If you have a warning that your fuel pump is going bad, you might hear a loud, whining sound that comes from the gas tank.


You rely on seamless fuel delivery when driving your vehicle and the fuel pump has you covered. With a little know-how and some simple maintenance tasks, you can keep your fuel pump in good condition for many years.