Bad Fuel Pump Symptoms, Causes (& Replacement Cost 2022)

If your car burns gas, then it has at least one fuel pump in the system. It’s one of the components that your engine can’t run without, even if the tank is full to the brim. The fuel pump is responsible for delivering fuel from the gas tank to the engine at the appropriate pressure required for performance demands. This article explains the bad fuel pump working, symptoms, and causes.

What is a Fuel Pump?

The fuel pump is a part of an automobile that supplies fuel from a fuel container to the carburetor or fuel injector of an IC engine

When the ignition key is turned on, the fuel pump is activated and pressurized, which can be heard as a quiet whine or hum in some cars. The fuel pumps on most modern vehicles are electric and mounted in the fuel tank.

Fuel Pump

However, some vehicles are equipped with inline or mechanical-style fuel pumps. Because the fuel pump is the component responsible for supplying the engine with the fuel required for it to run, any issues with it can cause major drivability and performance problems. 

Working of Fuel Pump

The plunger is driven by a bottom-mounted cam and tappet mechanism. The plunger reciprocates in the barrel. The number of cylinders in the engine equals the number of plungers in the engine. The plunger has a rectangular vertical groove that spans the length of it.

The delivery valve is lifted off its seat by the pressure of the gasoline on the spring. The fuel is supplied to the injector through the delivery valve.

When the plunger hits the bottom of its stroke, the supply port and spill are exposed, and fuel from a low-pressure pump is pushed into the barrel after filtering.

The cam action has now driven the plunger up, and both parts have been closed. As the plunger advances farther, the fuel above it is compressed, raising the delivery valve and delivering the gasoline to the injector.

The plunger continues to rise, and the helical groove connects the spill port to the fuel in the upper portion of the plunger via the rectangular groove at a given point. The delivery valve is driven back into its seat by the spring force as a result of the rapid pressure drop.

Furthermore, the pressure in the supply pipe falls. The injector’s nozzle discharge is abruptly turned off as a result. The cycle continues to repeat itself.

Whether the spill port is constructed to convey the high-pressure gasoline in the top portion of the barrel earlier or later affects the timing of each plunger stroke. The placement of the helical groove, which may be modified by rotating the plunger with the rack, determines this.

The rack is connected to the accelerator. It relates to a geared quadrant, in which the rack rotates, causing the gear quadrant to turn and the plunger to rotate as well. By pushing the accelerator pedal, the driver may control the fuel supply to the engine cylinder.

Symptoms of a bad Fuel Pump

As the fuel pump goes bad, it produces one of the below-given symptoms:

  1. Whining Noise
  2. Difficult Start
  3. Engine Sputtering
  4. Overheating engine
  5. Car Surging
  6. Decreased Fuel Pressure
  7. Loss of Power Under Stress
  8. Sudden Engine Stalls
  9. Engine Misfires
  10. Inability to accelerate
  11. Poor Fuel Economy
  12. Poor Performance When Climbing a Hill

1) Whining Noise 

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

Most fuel pumps will produce a quiet hum during their normal operation; however, an excessively loud whine coming from the fuel tank is usually a sign of a problem. There may not be enough fuel, a damaged pump, or contaminated fuel inside the system.

2) Difficult Start

If the fuel pump of your car can’t supply gasoline from the fuel tank to the engine, the vehicle will not start. The pump does not deliver adequate fuel in such conditions, making it difficult to start and drive the car. This is one of the most common signs of a bad fuel pump.  

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.

3) Engine Sputtering

A sputtering engine is one of the surest indicators of a faulty fuel pump— typically at high speeds. Should you be driving at a consistently high speed and the engine suddenly sputter before returning to normal operation, it may indicate issues within the fuel pump.

In this case, the fuel pump cannot provide a constant stream of fuel to the engine at the ideal pressure.

4) Overheating Engine

An overheating engine may also be a symptom of a malfunctioning fuel pump. A bad fuel pump may overheat and inadequately deliver gas to the engine, causing it to run hot and turn off while on the road.

In this scenario, your vehicle may start back up after overheating and shutting down, only to do the same thing a half-hour later. This scenario is a common sign of a bad fuel pump.

5) Car Surging

Irregular resistance inside the fuel pump motor may cause the vehicle to surge and indicate a fuel pump needing repair. Surging feels like the gas pedal has been used. However, it occurs at a random, consistent speed. If this happens often, it may be because of problems within the fuel pump.

6) Decreased Fuel Pressure

Low fuel pressure can lead to engine misfires, low acceleration, rough idles, and engine stalls. If your check engine light is on and your car has been stalling out, you may have a fuel pump failure. 

7) Loss of Power Under Stress

Another indication of a bad fuel pump is a loss of power when the vehicle is under stress — such as driving uphill or carrying a heavy load — or while accelerating. The engine shuts down because weakening parts of the fuel pump cannot keep up with the car’s heightened fuel demands in these situations.

In these circumstances, the car will feel like it is unable to go or maintain the intended amount of power. If the fuel pump is the cause, it means it can no longer regulate fuel pressure accurately and provide the appropriate amount of fuel to the engine.

8) Sudden Engine Stalls

As if without cause, your engine will stop running. At most any time. This can be a simple annoyance if idling in your driveway or downright dangerous if it happens on the road.

A description of just such an event is provided below (skip to: “A Real-World Example of Fuel Pump Failure”).

Read More: Causes of Engine Stalls

9) Engine Misfires

Misfires will be felt more than heard. A series of misfires will feel like the car is bumping through a bunch of large soft pillows. Because misfires can eventually damage your engine, correcting the related fuel pump problem as soon as possible is very important.

Read More: Causes of Misfires

10) Inability to Accelerate

Irregular resistance within the fuel pump motor can lead to your car slowing down and being unable to accelerate. Failing to accelerate is a good sign that your vehicle’s fuel pump needs inspection.

11) Poor Fuel Economy 

If your vehicle typically gets decent gas mileage and then suddenly starts hogging fuel, there could be an emergency under the hood.

Fuel pumps have a relief valve that will allow more fuel than necessary to flow into the engine system if it fails to open. 

12) Poor Performance When Climbing a Hill

We do not live in a flat world. Most of us, anyway. Hills abound, and meeting a hill, or other inclines your car can’t climb is just another indication the fuel system is calling it quits.

Read More: Symptoms and Causes of Bad Fuel Injector

Causes of a Fuel Pump Failure

A fuel pump goes bad due to one or more below given causes:

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

2) 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.

3) 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.

4) Damaged Fuel Lines

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

5) Restricted Fuel Filter

Some cars have an external fuel filter. If your fuel filter becomes clogged or needs to be replaced, the pump will have a harder time pushing fuel through.

Read More: Bad Fuel Filter Symptoms and Causes

6) Dirt and debris

Even though the pump has a strainer, smaller particles can make their way through, causing damage. So, if you’ve replaced your fuel pump recently and didn’t clean the tank before installing the replacement, the dirt and debris accumulated at the bottom of your gas tank can actually cause damage to the new fuel pump.

7) Normal wear and tear

Of course, fuel pumps don’t always fail due to outside forces, such as running the fuel tank low and contamination. It’s also very common for a fuel pump to simply wear out over time.

How to Remove Fuel Pump

Accessing and removing a fuel pump can be tedious, so you must ensure you do it correctly the first time. Use these tips for a successful job.

  • Be sure to relieve any pressure in the fuel line.
  • Additionally, make sure there is no live electricity near the fuel tank.
  • Take a photo of the fuel pump or use a marker to note where it is seated within the tank. This will help you align the pump correctly when you return it to the tank.
  • There might be dirt and grime around the top of the pump. Make sure you clean this area thoroughly and eliminate anything that could fall into your tank and cause issues later. Compressed air is a great way to blow things off.
  • Many pumps use a locking ring, which might be difficult to remove. Read how to remove it, and be aware that it might have different locking methods, which might be snapped off if you aren’t delicate.
  • Inspect your fuel sending unit and float while you’re down there. 

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 $210 to $1,070. In this cost, the costs of the parts are from $100 to $860 while the labor costs are from $110 to $310.

How to Avoid Fuel Pump Failure

  1. Don’t let your fuel level get below 1/8th to 1/4th of a tank.
  2. Change your fuel filter at 30,000-mile intervals (most vehicles).

FAQ Section

Can I drive with a bad fuel pump?

Because a bad fuel pump could cause unexpected drops in power or even completely shut the vehicle down, it is not recommended to drive with a bad fuel pump.

Is replacing a fuel pump difficult?

Replacing your fuel pump is not difficult and is something that almost anyone with basic hand tools can do. There are two types of fuel pumps, one is inline and located underneath your car, and the other is inside your gas tank. Both are simple to access.

How to start a car with a bad fuel pump?

Following are three methods to start a car with a bad fuel pump:

  • Engine Heat – The engine overheating due to a faulty fuel pump is possible, but if the car is shut off and cooled, the low temperature can also cause the pump to stall. Maintaining consistent heat to the engine can allow you to drive the car far enough to reach a repair shop.
  • Fuel Pressure Gauge – Attaching a fuel pressure gauge directly onto the engine will allow the car to start and drive. A fuel pressure gauge usually is in the $40 price range and is a handy tool to have available.
  • Manual Pressure – Using pressure to assist the fuel through the lines is another simple technique to start the car.

Where is the fuel pump located?

In most vehicles, the fuel pump is located in the fuel tank. 

What are the signs of a bad fuel pump?

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

How many years do fuel pumps last?

Fuel pumps are meant to last around 100,000 miles, but most people never have to replace their fuel pumps. They are typically built to last since they are positioned in a hard-to-access place within your fuel tank.

What does a bad fuel pump sound like?

A damaged fuel pump might make a loud, whining sound that you’ll hear from your gas tank. The pump may also make this noise if you’re low on fuel or the fuel in your tank is contaminated. The normal noise your pump makes is a low hum. Loud whining indicates there is a problem.

What is the fuel pump replacement cost for chevy?

The average replacement cost of a Chevrolet Silverado 1500 fuel pump is from $1,120 to $1,300. Labor costs are from $190 to $250 while parts are priced from $930 to $1,050.

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