10 Symptoms of a Bad Fuel Pump (and Replacement Cost in 2022)

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.

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Diagnostic Fault Codes: How They Help You

This light provides a warning, but it signifies mu

This light provides a warning, but it signifies much more. With this alert, the onboard diagnostic system gets busy and stores one or more diagnostic fault codes (DTC). These codes can be interpreted to tell you the nature of the problem.

A local auto parts store can generally evaluate the stored codes for you at no cost using a special tool called an OBD-II scanner. If you’re serious about doing you’re own automotive repair or maintenance, this automotive scan tool will usually pay for itself after a few uses.

However, while knowing what fault codes were triggered is helpful, it often proves far more beneficial to take your car or truck to a competent service technician. Such folks can provide accurate diagnosis as well as any needed repairs. 

Power Loss

Your engine might not sputter but you will lose power under certain circumstances if your fuel pump is going out. For example, imagine you’re driving up a steep hill and all of a sudden you lose power. This is a sign the fuel pump is not transferring enough fuel to the engine and it cannot handle the hill’s stress.

8. Car Will Not Start

Another more serious symptom of an issue with the fuel pump is a no-start condition. If the fuel pump fails completely — to the point of not being able to provide enough fuel for the engine to run, the vehicle will refuse to start. The engine will still crank when the key is turned, but it will be unable to start due to the lack of fuel. A no-start situation can also be caused by a variety of other issues, so having the vehicle properly diagnosed is highly recommended.

Fuel pumps are found on virtually all internal combustion engine-equipped vehicles in one form or another. Most fuel pumps are built to last. However, as the vehicle reaches high mileage, it is not uncommon for fuel pumps to require replacement. Another reason fuel pumps fail is regularly keeping . If your vehicle is displaying any of the symptoms above, or you suspect your fuel pump may be having an issue, have the vehicle inspected by a professional technician to determine if the pump should be replaced.

2. Difficulty Starting

Another symptom commonly associated with a problematic fuel pump is difficulty starting. Because fuel pumps constantly run whenever the ignition is turned on, they can eventually wear out and weaken over time. A weak fuel pump may still pump fuel, but the vehicle may experience difficulty starting from the lack of pressure. A weakened fuel pump can cause the vehicle to take more cranks to start than normal, and in more serious cases may even cause the vehicle to require multiple turns of the key before it will start.

Why Fuel Pumps Fail

What causes lie in wait to ambush you with this ki

What causes lie in wait to ambush you with this kind of problem? Here are some common ones:

Pump Issues

Late model automotive pumps are complex and may include pressure control and/or relief valves. Failure of these features can reduce output pressure or recirculate fuel back into the tank leaving none for the engine.

Fuel Problems

Contamination with sludge from that backcountry service station fill-up last week can gum up a pump or block its inlet screen. Reduced or zero flow will result.

Related: How to Dispose of Old Gas

Clogged Fuel Filter

If not replaced at normal service intervals, a fuel filter can become clogged with silt or even water. This can restrict fuel flow and cause pump failure symptoms. Reduced flow can also cause a pump to overheat resulting in permanent pump damage.

Damaged Fuel Line(s)

A tire-launched pebble can dent one or more fuel lines pinching fuel flow thus mimicking fuel pump failure.

Old Age

Things simply wear out with age. Age degradation can bring any pump to its knees though such would not be expected until well beyond 100,000 miles.

How to Fix a Bad Fuel Pump

If your car has developed any of these symptoms and needs a new fuel pump, it can make sense to replace it on your own. The project can be straightforward for older vehicles, and can take up to three hours to complete. Before you get started, you’ll need a few tools, including the new fuel pump assembly, a wrench and socket set, and protective gear. You’ll also want a block of wood or a jack stand to support the fuel tank.

Before you do anything, you should start by disconnecting your vehicle’s battery. Then drain the fuel tank (another option is to have driven the car so the fuel level is near empty). Some vehicles have a drain plug, which makes this much easier.

Disconnect the fuel lines and wiring, and then remove the fuel tank filler neck. Support the tank using your jack or block of wood, and then remove the straps connected to the fuel tank. You can now remove the fuel tank from the vehicle.

At this point, you should be able to remove the fuel pump. Follow these instructions in reverse order to install your replacement pump, and you should be good to go.

Different vehicles may require slightly different steps, so we recommend consulting a service manual for your specific vehicle application. And of course, you can always take your vehicle to a mechanic or the dealership for professional service.

Difficult Starts

If your vehicle’s fuel pump cannot get gas from the tank to the engine, you will have trouble starting your car. The car will struggle to start and run because the pump cannot push enough gas through. A worn pump loses its pressure and the engine is being starved of gasoline.

How Much Does It Cost To Replace a Fuel Pump?

Depending on the car and how old the car is, fuel pump costs range from $50 to several hundreds of dollars.

How a Fuel Pump Works

You may know that an internal combustion engine works by burning fuel and air. Your vehicle’s fuel pump plays a critical role in this process, sending gas from the tank through the fuel lines to the injectors for timed fuel delivery to each cylinder. Depending on your vehicle, the pump will either be mechanical or electric. Many modern cars use an electronic fuel injection system.

A properly functioning fuel pump maintains the ideal level of fuel pressure that your vehicle needs to run correctly. Excessive pressure can lead to the engine running rich, which means that the fuel mixture doesn’t have enough oxygen. Low pressure can lead to the engine running lean, and not having enough gasoline in the mix. Both scenarios can affect your car’s power and fuel efficiency.

Your vehicle’s fuel filter also plays a critical role, keeping debris out of your fuel pump. This is an important maintenance item that should be replaced every 30,000 miles. Additionally, a bad fuel filter can produce issues similar to those caused by a bad fuel pump. For more details, we’ve put together a helpful guide on how to change your fuel filter.

Losing Power when the Vehicle is under Stress

When climbing a hill or hauling heavy cargo, your car is under stress. If you lose overall power while performing stressful tasks with your vehicle, your fuel pump may be too weak to keep up with the demands of driving.

Lower Fuel Efficiency

Because your fuel pump is pushing too much fuel into the engine you’ll burn more gas than normal. This means more trips to the gas station to feed your car, truck, or SUV. If you track how much mileage you get between fills and notice a drop, it could be your pump.

Symptoms of a Failing Fuel Pump

Although mechanical and electronic pumps fail for different reasons, the symptoms of failure are similar for both types of pumps. If you notice any of the common symptoms of fuel pump failure while you’re driving, you may need to have your fuel pump inspected and replaced.

1. You Might be Experiencing Fuel Pump Failure if Your Car Jerks or Sputters at High Speeds

If you’re driving at freeway speeds and notice your engine sputter or jerk, you may have a failing fuel pump. This problem is caused when the fuel pump can’t deliver a smooth flow of fuel to the engine; periodically, your engine receives only air when it was expecting to receive fuel. This interruption in fuel flow causes your engine to skip several power strokes, forcing the engine to sputter and jerk. In the early stages of failure, this sputtering may only last for a minute or so before the engine returns to normal operation. Some drivers may confuse this sign with the effects of dirty gas, but modern fuel standards make a failing fuel pump more likely.

2. Your Fuel Pump Might Be Failing if You Lose Power When Accelerating

If you notice that your car often loses power when you try to accelerate from a stop, your fuel pump may be in trouble. Accelerating requires more fuel, forcing your fuel pump to work harder. If your pump is failing, it may not be able to keep up with this increased demand, starving your engine of fuel as it tries to accelerate. If your car acts like it’s about to stall when you try to accelerate from a stop, you may need to have your pump inspected.

3. Your Fuel Pump Might Be a Problem if you are Losing Power While Driving Uphill or Towing a Load

Certain driving activities, such as climbing a hill or towing a load, place an extra strain on your engine and demand more fuel to deliver the same performance. When your fuel pump isn’t on top of its game, it often can’t keep up with this increased fuel demand. These demanding situations increase the strain on your pump, causing the weak elements to fail. With the flaws in your weakened pump exposed, it isn’t able to maintain a steady flow of fuel to the engine, resulting in a loss of power.

4. Your Fuel Pump Might Be Failing if Your Engine Surges

As your fuel pump begins to wear out, its components often wear down at different rates. When this mismatch becomes great enough, the pressure in your fuel lines can become inconsistent. In these circumstances, drivers may find their cars suddenly accelerating for a few moments even when they haven’t pressed the gas pedal, a condition known as surging.

5. Fuel Pump Failure Might Be a Reason Why Your Engine Won’t Start

If you ignore all of the other warning signs of a failing fuel pump, it will eventually fail completely. Once your fuel pump has finally given up the ghost, no fuel will reach your engine. You may hear your spark plugs firing when you try to start your car, but without fuel, the engine won’t be able to turn over. Of course, there could be other explanations for your engine’s failure to start besides a failed fuel pump. To confirm that your pump has failed, check the pressure in your fuel lines with a fuel pressure gauge; if it reads zero, then your pump is likely dead. You can also check your car’s fuse box; a blown fuel pump fuse is another reliable symptom of a failed pump.

FAQs About Fuel Pumps

FAQs About Fuel Pumps

You’ve got questions, The Drive has answers!

Q: How does a car act when the fuel pump is going out?

A: If your fuel pump is going bad or has died, you will likely experience one or more of the many symptoms detailed above. These include trouble starting, sputtering, weak performance, poor fuel economy, poor acceleration, and overheating.

Q: Would a bad fuel pump throw a code?

A: Although a bad pump itself doesn’t throw a code, the incorrect amount of fuel sent through a car’s fuel system could trigger sensors that anticipate certain levels and ratios of air and fuel mixtures. So technically, yes, it’s possible to see a code as a result of a bad fuel pump.

Q: Can you drive with a bad fuel pump?

A: Because a bad fuel pump could cause unexpected drops in power or even completely shut the vehicle down, we do not recommend driving with the knowledge of a bad fuel pump.

Q: How do you clean a fuel pump without removing it?

A: Fuel system cleaners do exist, but even in the event that they actually do something (don’t count on it), it will simply be putting the job off to a later time. Get it out of the way and do the full job now before something bad happens later when you aren’t expecting it.

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