What are the Symptoms of Bad Fuel Pump? | What are the Signs of Bad Fuel Pump?

If your vehicle burns gasoline, there is at least one fuel pump in your system. It is one of the most vital parts of your vehicle. Your car engine can’t operate without this part, even if the fuel tank is full. The fuel pump is used to deliver fuel from the tank to the engine at the correct pressure according to the engine requirements. This article explains the bad fuel pump symptoms, causes, and replacement costs.

What is a Fuel Pump?

A fuel pump is a part of a vehicle that pumps fuel from a fuel tank to the carburetor or fuel injector of an IC engine

Fuel Pump

As you turn on your vehicle’s ignition key, the fuel pump starts working and starts pumping fuel from the fuel tank to the engine combustion chamber. In the case of some cars, when the fuel pump is operating, it generates a faint squeak or hum noise which can be heard in your car.

The latest cars contain electric fuel pumps installed in the fuel tank. But some old vehicles still have mechanical or inline fuel pumps.

As the fuel pump goes bad, it generates one or more symptoms such as poor engine performance, poor fuel economy, loss of power under stress, difficult start, whining noise, check engine light illumination, inability to accelerate, engine misfiring, engine sputtering, engine overheating issues, vehicle surging, or insufficient fuel pressure.

Symptoms of a bad Fuel Pump

  1. Loss of power under stress
  2. Poor performance when climbing a hill
  3. Whining noise
  4. Decreased fuel pressure
  5. Inability to accelerate
  6. Difficult start
  7. Poor fuel economy
  8. Car surging
  9. Engine sputtering
  10. Engine misfires
  11. Engine stalling
  12. Overheating engine

1) Whining Noise from the Fuel Tank

One of the first symptoms of a bad fuel pump is a loud whining sound. An old or worn fuel pump may produce a noticeably loud whine or howl while running.

Unusual Noise When Accelerating

Your pump may also produce extreme noise due to the damaged pump bearings.

The pump can also produce excessive sound due to contaminated fuel or insufficient fuel in the fuel tank. If your pump is operating normally, there will be no or very low noise. An excessive noise indicates a problem.

2) Overheating Engine

The overheating engine can also be a sign of a faulty fuel pump. A faulty fuel pump can’t properly supply deliver fuel to the engine due to that your engine may overheat and shut down while driving on the road.

engine overheating duel to bad fuel pump

In this case, the vehicle can be restarted after overheating and turning off, but only 30 minutes later. This condition is a clear symptom of a faulty fuel pump.

Read More: Causes and Symptoms of Engine Overheating

3) Engine Sputtering

The engine sputtering is one of the most reliable signs of a bad fuel pump (usually at high speeds). If you constantly drive fast and the engine unexpectedly stalls before returning to normal operation, there may be a problem with your pump.

In such conditions, the fuel pump can’t properly supply the fuel to the engine.

Engine Sputtering, symptoms of bad fuel pump

4) Difficult Start

The difficult start is one of the major signs of a bad fuel pump. If the fuel pump of your vehicle doesn’t pump gasoline from the gas tank to the engine, the vehicle will not start. If your fuel doesn’t pump fuel efficiently, it will make your vehicle difficult to start. 

Hard Starting Condition due to bad map sensor

In such conditions, the worn pump fails to gain pressure, and the engine runs out of fuel. Sometimes your car can’t start due to the fuel filter, starter, alternator, and battery problems.

5) Car Surging

Uneven resistance within the fuel pump motor may lead your car to jump, which indicates that your car’s fuel pump needs repair.

Car Surging due to bad fuel pump

The feeling of surging is like stepping on the gas pedal. However, this happens randomly and at a constant speed. If this issue occurs frequently, it could be due to a problem with your fuel pump.

6) Poor Fuel Economy 

When your vehicle demands more fuel than normal to fill up the fuel tank, there may be a problem with the fuel pump. This situation indicates that your pump valve is not properly opening, and it needs too much fuel to inject inside the engine. The extra fuel inside the engine doesn’t store or used.

Poor fuel economy

7) Loss of Power Under Stress

The low engine power under load is one of the common symptoms of a bad fuel pump. 

In this situation, the engine stops because the weakened part of the fuel pump cannot meet the increased fuel demand of the vehicle.

In these conditions, the car cannot drive or maintain the required performance. In the case of the fuel pump, this means it can no longer fine-tune the fuel pressure to deliver the correct amount of fuel to the engine.

8) Engine Misfires

A bad fuel pump may lead to the engine misfiring issues. There may be more misfires than you’ve heard. A series of misfires may feel like your vehicle hitting a big pile of fluffy pillows.

engine Misfiring, signs of bad fuel pump

Misfiring is very dangerous for your engine. It can ultimately damage the vehicle engine or other vehicle’s internal parts. Therefore, you should immediately find the bad fuel pump and repair or replace it.

9) Engine Stalling

The engine stalling is one of the clear symptoms of a bad fuel pump. This is an easy annoyance when you’re idling in your driveway and can be very hazardous if it occurs on the road.

engine Stalling

10) Inability to accelerate

Uneven resistance within the fuel pump motor may cause the vehicle to slow down and not be able to accelerate. If it doesn’t accelerate, that’s a good sign that the vehicle’s fuel pump needs to be checked or replaced.

acceleration problems due to bad fuel pump

11) Low Fuel Pressure

A reduction in the fuel pressure may cause engine stalls, poor acceleration, idling, and misfiring. If the pressure gauge on your car dashboard is showing low fuel pressure, it means that your fuel pump may be defective.

Fuel pressure Gauge

12) Poor Performance When Climbing a Hill

Most of us don’t live in a flat world. Hills abound and driving up hills, or other inclines that your car can’t climb is another sign of a bad fuel system.

Read More: Fuel Pump Working and Types

Causes of a Fuel Pump Failure

Following are the major causes of a bad or faulty fuel pump:

  1. Pump issues
  2. Clogged fuel filter
  3. Normal wear and tear
  4. Old age
  5. Damaged fuel lines
  6. Fuel problems
  7. Dirt and debris

1) Pump Problems

The old models of fuel pumps have complicated designs. These pumps also contain relief valves and pressure control valves.

The failure of the relief valve or pressure control valve is one of the major causes of a fuel pump to go bad. If these parts fail, the outlet pressure will drop, or the fuel will flow back into the fuel tank with nothing remaining in the engine.

2) Damaged Fuel Lines

The fuel flows inside the fuel lines. These lines connect the different parts of the engine. The fuel lines supply fuel to various parts of the engine. A stone fired from a tire can dent one or more fuel lines and pinch fuel flow, causing the fuel pump failure.

3) Age of the Pump

The engine parts wear out with time. The age of the fuel pump is one of the common causes of pump failure. Aging can bring any pump to its knees, but that only happens after 100,000+ miles.

4) Dirt and debris

Even if your pump has a fuel filter, small particles can get through it and damage it. Therefore, if you recently changed your pump and didn’t remove contamination from the fuel tank before installing the pump, the contamination that collects at the tank base may damage your new fuel pump.

5) Clogged Fuel Filter

The vehicles contain an external fuel filter. The main function of the fuel filter is to remove the solid dirt from the fuel and then transfer clean fuel to the engine. As the fuel filter goes bad or becomes clogged, the fuel pump may have fuel delivery issues.  

6) Fuel Problems

The contaminated fuel is a major cause of a bad fuel pump. The contaminated fuel may block the different parts of the fuel system (such as the fuel injector, fuel rails, or fuel pressure sensor) and may badly damage the engine parts.

Therefore, as you notice the symptoms of a bad fuel pump, firstly, you should check the fuel. If your fuel is dirty, then change it.

7) Normal wear and tear

The fuel pump doesn’t always fail due to external factors, such as low fuel in the tanks or contamination. It is also common for fuel pumps to wear out over time.

How to Replace a Fuel Pump

Replacing or removing a fuel pump may be boring, so you must ensure you do it correctly the first time. Follow the below-given steps to replace your fuel pump:

  1. Put on your safety glasses and have a fire extinguisher nearby.
  2. Safely raise and support the rear of the vehicle using a jack and jack stands. Set the parking brake and chock the front wheels.
  3. Disconnect the negative battery cable.
  4. Relieve fuel system pressure following the procedure found in the factory repair information.
  5. Drain the fuel tank if it has a lot of fuel. Usually, this is done using a hand-operated pump or siphon. If you choose to leave the tank full, it will be a lot heavier and harder to balance.
  6. Loosen the clamp on the fuel filler neck, then disconnect the neck from the fuel tank.
  7. Support the fuel tank with a transmission jack or equivalent.
  8. Remove the fuel tank strap bolts and the straps themselves.
  9. Lower the tank just enough to access and disconnect the fuel hoses, electrical connections, and emissions hoses.
  10. Once everything is disconnected, lower the tank completely.
  11. Clean the area around the pump access hole to prevent dirt and debris from entering the tank.
  12. Remove the retainer ring or bolts securing the pump assembly to the tank.
  13. Remove the fuel pump and seal ring from the fuel tank.
  14. Compare the replacement pump to the new pump assembly to ensure a match.
  15. Install the new seal ring and new pump assembly in the tank.
  16. Using a transmission jack or equivalent, raise the tank just enough to reconnect the fuel hoses, electrical connections, and emissions hoses.
  17. Raise the tank into place.
  18. Reinstall the fuel filler neck and secure it with a clamp.
  19. Reinstall the fuel tank straps and torque the mounting bolts to the specification listed in the factory repair manual.
  20. Safely remove the jack stands and lower the vehicle.
  21. Reconnect the negative battery cable.
  22. Fill the fuel tank as needed.
  23. Start the vehicle and double-check your work, looking for leaks.

How to diagnose a bad Fuel Pump

Following the below-given steps to diagnose a faulty fuel pump:

  1. Check the fuel level and add more if needed.
  2. Inspect the wiring connected to the fuel pump
  3. Check the pump fuse and replace it if needed.  
  4. Repair or replace the bad relay fuse
  5. Inspect and fix the clogged fuel filter
  6. Inspect the fuel injectors and replace them if needed
  7. Inspect the range of the fuel pressure

Fuel Pump Replacement Cost

The replacement or repair cost of the fuel pump varies according to your living area, labor cost, and the type of part’s brand. The average replacement cost of a fuel pump is from $220 to $1,090. In this cost, the costs of the parts are from $100 to $860, while the labor costs are from $110 to $310.

FAQ Section

How to start a car with a bad fuel pump?

Follow the below-given methods to start your car with a bad fuel pump:

  1. Fuel Pressure Gauge: Connecting the fuel pressure gauge directly to the engine allows the car to start and run. Often in the $50 price range, a fuel pressure gauge is a useful tool.
  2. Engine Heat: A faulty fuel pump can cause the engine to overheat, but low temperatures can also cause the pump to stop when the car is off and cooling down. You can drive the car to the workshop if you keep the engine warm.
  3. Manual Pressure: Utilizing pressure to force fuel through the fuel lines is another easy method for starting your vehicle.

Can I drive with a bad fuel pump?

Driving with a faulty fuel pump is not recommended, as it can lead to an unexpected loss of power or even a complete stop of the vehicle.

Is replacing a Fuel Pump Difficult?

The fuel pump replacement is not tough and can be done by anyone with basic tools. The fuel pumps have two types:  one is inline installed under the car, and the other is installed in the fuel tank. Both are easily accessible.

How many years do fuel pumps last?

A fuel pump may last about 100,000 miles, but most people don’t need to replace their fuel pump. They are usually durable as they are located in inaccessible places inside the tank.

Where is the fuel pump located?

The fuel pump is most usually located in the fuel tank. 

What is the fuel pump replacement cost for chevy?

The average replacement cost of a Chevrolet Silverado 1500 fuel pump is from $1,110 to $1,400. In this cost, the cost of the parts is between $920 to $1,060, while the labor costs are from $190 to $340.

What does a bad fuel pump sound like?

A bad fuel pump can cause a loud noise to be heard from the fuel tank. The pump can also make this noise when it is low on fuel or the fuel in the tank is contaminated. Normal pump noise is a low hum. A large whining noise shows an issue with your pump.

What are the signs of a bad fuel pump?

  1. Loss of power under stress
  2. Poor performance when climbing a hill
  3. Whining noise
  4. Decreased fuel pressure
  5. Inability to accelerate
  6. Difficult start
  7. Poor fuel economy 
  8. Car surging
  9. Engine sputtering
  10. Engine misfires
  11. Engine stalling
  12. Overheating engine

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