Car Care Tips

Tips to keep your car on the road.

Maintenance April 29, 2022

What Happens When a Fuel Pump Goes Out?

What happens when a fuel pump goes out?

The fuel pump in your vehicle does exactly what you would think— it pumps fuel from the gas tank to the engine to power your car. (There are some other steps in between, but we’ll get to those.)

Given the crucial role of the fuel pump in making your car move, it’s a car part you ought to know more about. We’re walking through the warning signs of a bad fuel pump and what happens when your fuel pump goes out.

What Does A Fuel Pump Do?

Modern vehicles with an internal combustion engine are equipped with an electric fuel pump. Most cars have an in-tank pump mounted within the fuel tank, although some have an inline pump located between the gas tank and the engine.

By understanding the basic process of the fuel pump, you’ll have a better understanding of what happens when a fuel pump goes out—and how to recognize when it’s happening.

  1. Fuel in your tank is drawn up through a line that heads toward the engine.  If your fuel pump is electric, it’s operated by a small motor that draws the fuel sitting in your gas tank up through a fuel line. In older vehicles with mechanical fuel pumps, the pump moves as your camshaft spins and fuel is drawn through a line using suction.
  2. Fuel travels through the fuel line and toward the carburetor or the cylinder. Depending on your engine makeup, your fuel line will go directly to the cylinder or will have a pit stop elsewhere.
  3. Air is injected into the fuel to create a mixture. 
    • In carbureted engines, fuel is injected with air and forms a mixture in the carburetor. Then, the mixture heads toward the cylinder.
    • In a fuel-injected engine, fuel and air don’t mix until they reach the cylinder. (Most modern vehicles have a fuel-injection system.)
  4. The fuel combusts, creating energy. Within your cylinder, the ignited fuel and air mixture is compressed by the piston. As the piston moves and the fuel mixture becomes more compressed, a spark plug provides a spark to ignite the mixture and the piston fires.
  5. The released energy now powers the crankshaft. You’re officially on the move. That fuel has successfully moved your car further down the road and is being expelled as exhaust after its useful life.

That five-step process has dozens of smaller steps in between, but it all starts at the fuel pump. If the fuel you’ve put into your tank can’t make its way to the engine to be mixed with air, steps two through five aren’t happening, and you’re not making progress down the road.

What Happens When a Fuel Pump Goes Out?

A failing/failed fuel pump will cause major performance and drivability issues with your vehicle. If your fuel to air ratio is off and the cylinders aren’t getting enough fuel, then the pistons aren’t firing and your engine is struggling to move the vehicle forward. We’re not just talking about lower gas mileage or inefficiencies. If your fuel pump is bad enough, your car won’t start!

How long does a fuel pump last? Because of the important role they play, fuel pumps are meant to be tough and withstand almost the entire life of your car. You typically don’t have to replace your fuel pump until you have at least 100,000 miles on your vehicle, and fuel pumps have been known to last more than 200,000 miles!

Warning Signs of a Bad Fuel Pump

If your car is experiencing any of these bad fuel pump symptoms, bring it in for a vehicle checkup!

  1. The car won’t start.
    If the vehicle is struggling to start or isn’t starting at all, your fuel pump may be damaged or clogged. If the car still cranks when the key is turned but won’t start, it may be because fuel isn’t getting to the engine. Or if the car starts but requires more than the average number of cranks to turn over, the fuel pump could be at fault then too.
  2. The car sputters or dies while driving.
    It’s never a good sign when your car dies as you’re driving. If your engine is sputtering or stalls in the middle of your drive, your fuel pump is likely the issue. The low pressure caused by a faulty fuel pump means that your engine isn’t getting the fuel and air mixture it needs to initiate combustion and power the car. This may be especially obvious when your vehicle is accelerating or under stress (ex: towing a heavy load or driving uphill).
  3. The engine surges while driving.
    Another common symptom of a bad fuel pump is a surging engine. This is caused by too much fuel being sent to the engine. When that happens, you’ll notice your engine surging—the vehicle will repeatedly pick up speed and then drop speed, even though you haven’t touched the gas pedal or the brake.
  4. You hear whining in the backseat.
    Nope, not children—your fuel tank. If your fuel tank is making a low-grade whining or whirring noise, that’s a bad sign. Your fuel pump makes a low, barely noticeable humming sound when running normally. If the pitch increases significantly, you’ll want to get it looked at by one of our experienced mechanics at Virginia Tire & Auto.
  5. You notice lower gas mileage. Another symptom of a bad fuel pump is poor fuel efficiency. Damaged or worn components in the fuel pump can let excess fuel into the engine that goes to waste.

Sometimes the symptoms of a bad fuel pump can be caused by other issues, such as bad fuel, damaged fuel lines or a clogged fuel filter. In any case, you’ll need a comprehensive inspection and diagnosis by a qualified technician to get to the heart of the issue.

There are a few maintenance tips that you can follow to make your fuel pump last longer:

  • Always keep your gas tank at least a quarter of the way full. Gasoline works as a coolant for in-tank fuel pumps. If you’re constantly running close to empty, the fuel pump has to withstand more heat, shortening its lifespan. Low fuel levels also require the pump to work harder to move fuel.
  • Perform regular fuel system maintenance. Make sure your fuel system and fuel filters are regularly inspected and replaced when necessary. By scheduling regular maintenance, you can avoid potential issues.

Read: What Is Fuel Induction Service? 7 Signs Your Car Needs Fuel Cleaning

The Heart of Your Car

Your fuel pump serves as the heart of your vehicle, pumping fuel away and into the parts of the car that need it to do their job. You can trust the heart of your car to the professionals at Virginia Tire & Auto. We know about the importance of regular fuel system maintenance and are equipped to handle even the most complicated fuel pump replacement.

At Virginia Tire & Auto, we want your vehicle to be running smoothly mile after mile. If you’re experiencing issues and you think it may be a fuel pump problem, it’s best to get it checked out. Stop in any of our auto repair locations to talk with one of our professional mechanics or schedule a service visit online.

We offer a 24-month/24,000-mile warranty, plus all Virginia Tire & Auto customers are eligible for up to $200 of roadside assistance coverage for 365 days!

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