10 Bad Fuel Pump Symptoms and Causes

The fuel pump takes fuel from the tank and supplies it to the engine for the car to function seamlessly. If the pump becomes faulty, overheats, or fails, the engine will not receive fuel to run the car.

If you are experiencing these 10 signs, then it may be time to head over to your local dealership for a fuel pump replacement.

What Is A Fuel Pump, And How Does It Work?

A fuel pump is a small electric motor that delivers fuel from the tank to the engine. In older vehicles, a fuel pump is positioned along the frame rail and is mechanically fastened into the fuel line.

With classic cars, mechanical fuel pumps are located at the front of the engine and utilize a pull-style pumping mechanism, making them more appropriate for traditional fuel dispensing. In comparison, new cars have fuel pumps located at the end of the back-fill pipe, enabling them to push rather than pull fuel.

In contemporary vehicles, however, almost all use a pump located within the fuel tank. This little cylindrical pump is part of a bigger figure alongside a fuel level sensor and a fuel filter screen.

Pumps are generally capable of producing greater pressure by displacing fluid towards the destination using the pipe rather than dragging it up through the piping system.

Modern fuel pumps utilize an impeller-style system that allows fuel to be drawn through it and simultaneously creates positive pressure on the engine side of the pump.

There rround style as well as a rotary vane and gerotor pumps that can be used on some vehicle parts but are rather uncommon to come across.

Once the pump builds pressure, it is designed to maintain it by blocking fuel from bleeding back into the fuel tank.

In such a way, your fuel stays in the line, ready to enable quick engine starts whenever necessary.

Related Post: What is a Fuel Pump?

Bad Fuel Pump Symptoms

If you notice any of the symptoms suggesting your fuel pump is bad, it’s advisable to take your vehicle for a checkup.

#1. Whining Noise from The Fuel Tank.

A whining sound coming out of your fuel tank is the primary and biggest sign of a failing fuel pump. An old or worn fuel pump whine may be louder than usual while running.

Almost all fuel pumps will make a quiet hum, but an unusually and excessively loud whine coming from the fuel tank indicates that there is a problem. This problem can stem from a lack of sufficient fuel or a damaged pump and even contaminated fuel within the system.

#2. Difficulty Starting.

Difficulty starting your vehicle is yet another symptom that often accompanies a problem fuel pump. Because fuel pumps work every minute the ignition is on, they can wear out over time.

Although a weak fuel pump will still pump fuel, starting the vehicle may become a challenge due to a lack of sufficient pressure.

A weakened fuel pump can make starting the vehicle require more cranks than usual, and in worse scenarios, may also cause the vehicle to need turning of key to start several times.

#3. Engine Sputtering.

An engine that sputters is essentially an indicator of a failing fuel pump, especially when it happens at higher speeds.

If you maintain a particular speed and you notice your engine sputters and then suddenly goes back to normal, it could mean that your fuel pump is faulty. In this instance, the pump is unable to maintain a steady supply of fuel to the engine at the required pressure, causing it to act erratically.

#4. Power Loss.

Another indication of a bad fuel pump is loss of power when the vehicle is strained, like during acceleration, going uphill, or driving with a heavy load.

In these scenarios, the engine gradually shuts down as fuel demand climbs because there are certain components inside the pump that weaken and fail to meet the steady demands.

The car will struggle to move or use the amount of power that is required of it. If there is a problem with the fuel pump, it means it is no longer capable of controlling the fuel pressure and providing the necessary fuel to the engine, which subsequently affects the overall performance of the car.

If the fuel pump’s relief valve does not open properly, too much fuel will enter the engine system resulting in power loss.

#5. Decreased Mileage.

One indicator of having engine problems is when the car starts using gas inefficiently, whereas it usually performs well. If you have been noticing visiting a gas station frequently, then it is time that you visit a mechanic nearby.

#6. Car Surging.

There is irregular resistance within the fuel pump motor, which directly impacts the fuel performance of the vehicle. With such irregular functioning, it feels as if there has been use of the accelerator pedal, however, with such consistent speed.

#7. Check Fuel Pressure.

Observing your fuel pressure gauge closely is important as it will indicate how much fuel is being sent to the engine. While observing the gauge, ask someone to rev the car.

You can consult your owner’s manual to figure out what the expected values are. In the case that your fuel pump is failing, it is safe to say that the gauge reading would undoubtedly be too low.

#8. Check Engine Light Comes On.

With the introduction of newer models, the sensor system has become more adept in identifying problems associated with the fuel pump, tracking the problem through the ECU, which consequently turns on the check engine light.

If not enough pressurized fuel is sent through the injectors, a ‘P0171 system too lean‘ code will be set in the control module which will trigger the check engine light.

#9. Stalling At High Temperatures.

Increased stalling of the vehicle may arise due to a variety of reasons. However, you should analyze the problem when it coincides with high temperature readings as the higher it gets, the more frequently the stalling will become. This frequently occurring problem is generally synonymous with troubles in the fuel pump motor.

Once the temperature gauge reaches a certain level, if stalling becomes a persistently observable problem, it would be safe to say that the fuel pump needs replacement.

#10. Car Will Not Start.

A no-start condition is a fuel pump symptom that is more severe than other symptoms. The vehicle will not start if the fuel pump has failed to the extent that it cannot deliver adequate quantities of fuel for the engine to operate.

The vehicle’s engine is able to crank when the key is engaged, but due to inadequate fuel, the engine is unable to start. Like any malfunction, a no-start situation can stem from other problems as well, thus a complete diagnosis of the vehicle is crucial.

Related Post: Top Reasons Why Your Car Won’t Start

What Happens When a Fuel Pump Goes Out?

If a car runs with a bad or broken fuel pump, the car will face serious fuel efficiency and performance issues that will affect its ability to drive. The pistons will not move because the engine is having problems pumping fuel to the cylinders to get the car moving. As a result, the fuel-to-air ratio will be misplaced, causing pistons to not fire.

In this case, gas mileage is the least of your concerns. If the fuel pump stops working altogether, then the car fails to start!

How long does a fuel pump last? Due to the importance of a fuel pump, fuel pumps are designed to withstand almost the entire life of the car in tough conditions. On average, a fuel pump is not required to be replaced in a vehicle until it completes more than 100,000 miles of a journey, and it is well known that some pumps do survive more than 200,000 miles.

What Is the Fuel Pump Replacement Cost? 

A fuel pump replacement is expected to cost the owner somewhere between $750 to $1300 based on the age, location, and type of the car.

The owner should also expect to pay $600 to $700 in labor costs, along with a parts cost between $500 and $600 to complete the fuel pump replacement. These estimates are pre-tax and do not include additional fees.

Factors affecting prices for fuel pump replacement

Drivers are often met with the decision to replace their fuel pumps. There are a number of considerations that one must keep in account while doing so, including:

• Vehicle make and model. More recent, premium, or oversized cars are typically more costly to fix than other makes.
• Where do you live. Different regions have different labor costs, which can significantly influence the other expenses you incur when getting a fuel pump replacement.
• Cost of the pump. An OEM part is, without doubt, the costliest option, seeing as you would have to source it directly from the manufacturer of your car. Usually, aftermarket pumps are less expensive.
• Diesel vs. gasoline engine. Most diesels have two fuel pumps: one in the fuel compartment and one closer to the engine. If you drive a diesel and both pumps need to be replaced, you’ll spend more on parts.
• Warranty coverage. A fuel pump is generally covered under the manufacturer’s powertrain warranty. Always check your warranty coverage before paying out of pocket for a fuel pump.

A Real-world Example of Fuel Pump Failure

Fuel pump issues can arise on their own, both in the form of fuel pump failure and fuel pump performance problems usually do not overlap with any other issues.

Visualize traveling to work on a freeway one day and all the sudden, your trustful car loses power and simply comes to rest without warning. Not only is this situation awkward during the moment, this situation can also put you in danger just pulling over to the breakdown lane.

So, after some time, you attempt to start the car, and it starts right up. Wonderful! After starting the car, you attempt to merge it back into the traffic. Everything appears to be just fine until the same malfunction occurs a few minutes, hours, or even days later. A dependable-seeming companion transforms into an unreliable monster who has decided to let you down whenever you least expect it.

This type of intermittent problem can bother you countless times until the failing pump ultimately dies and inevitably makes you stranded in the middle of nowhere.

Why Fuel Pumps Fail

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

Pump Issues

Newer car pumps are more sophisticated than older ones. For instance, modern ones have a more advanced pressure control system that may feature pressure relief valves.

Failure of these systems can either reduce the output pressure or recirculate the fuel back into the tank, resulting in none being available for the engine to use.

Fuel Problems

Contamination from sludge due to last week’s fill-up from a backcountry service station can clog a pump or block its inlet screen. Reduced or zero flow will result.

Clogged Fuel Filter

During periodic checks, the fuel filter and silt require replacement; otherwise, they can become clogged due to silt and water. This eventually delays fuel flow, which causes the pump to fail. Lowered fuel pressure or flow can lead to overheating of the pump and motor, subsequently causing permanent damage to it.

Damaged Fuel Line(s)

One or more fuel lines may get poorly deformed due to a pebble assaulted by a tire. These deformations may be so unfortunate that fuel flow gets pinched, mimicking fuel pump failure.

Old Age

Worn with time, one definitive aging decay is enough to literally bring a pump to its knees, and in this case is not expected until more than 100,000 miles are traveled.

An Early Warning from Your Instrument Panel

Your instrument panel can be functional when it comes to problems in the fuel system. It can signal the chance of trouble with the fuel system in advance so that you do not get left stranded.

How might you say? Think of that cautionary “Check Engine/Service Engine Old” you may recognize having seen. It would light up as you turn the key, briefly illuminating before going off. Next time you get into the vehicle, check for it.

Your owner’s manual will provide information on both the location and what this light looks like. Any vehicle manufactured after 1997 will include this feature, so rest never with this warning.

Diagnostic Fault Codes: How They Help You

Although this light serves as a warning, it can mean much more. In this case, the onboard diagnostic system gets to work and saves one or more diagnostic fault codes (DTC) with this alert. The codes can be analyzed to provide relevant information concerning the issue.

Most local auto parts stores will check the codes for you at no charge with an OBD-II scanner. If you are serious about performing your own automotive maintenance or repairs, this scan tool is usually worth the investment after a few uses.

Although it is beneficial to know the codes that were logged, it is often more helpful to take your vehicle to a qualified service technician. Such people will provide a correct diagnosis and perform any additional repairs that may be required.

At the Repair Shop

Now, the difficult part. In the event that your technician determines the fuel pump to be the source of your fuel system issue, it could be expensive to replace. Also, the new pump may need to be ordered. You may need to leave your favorite ride at the shop while it waits on that part.

Under these circumstances, most dealers will provide a loaner vehicle that can be used until repairs on your car are completed. Otherwise, they will at the very least be able to provide you with a lift back to your home if you are waiting without transport.

These services are rarely available for independent repair shops. With adequate resources or quick access to a replacement part, the process should take no more than two to three hours.

FAQs.