7 Bad Fuel Pump Symptoms To Watch Out For (+Fixes & Cost)

Does your car stall often or doesn’t easily start?
Those subtle changes could be indicative of a faulty fuel pump. These symptoms could lead to unexpected breakdowns and costly repairs if left unaddressed.

Eager to know the most common bad fuel pump symptoms?
Or how to replace a faulty fuel pump?

Don’t worry. We’ve got you covered.
Explore the seven fuel pump symptoms, how to replace a bad fuel pump, and the replacement costs.

This Article Contains

7 Faulty Fuel Pump Symptoms to Watch Out For
How to Replace a Faulty Fuel Pump? (Step-By-Step)
4 Fuel Pump Related FAQs

Ready?
Here we go!

7 Faulty Fuel Pump Symptoms to Watch Out For

Bad fuel pump symptoms can appear for several reasons, including wear and tear, electrical problems, or rough driving. Luckily, you can spot a weak fuel pump early with these eight clear signs:

1. Whining Noise

Fuel pumps have a fuel filter to prevent debris and contaminants from entering the pump. If this fuel filter becomes damaged or clogged, it can restrict fuel flow from the fuel tank to the engine. This fuel pump malfunction makes it challenging to maintain the required pressure, resulting in a whining noise.

Note: Besides a fuel pump issue, vacuum leaks in the engine’s intake manifold or vacuum lines and problems with the timing belt can also lead to a whining noise.

2. Poor Fuel Efficiency Or Gas Mileage

A malfunctioning fuel pump can disrupt the fuel flow from the tank to the engine. This can be influenced by fuel rail pressure sensors or fuel injector issues, leading to uneven fuel flow among the engine’s cylinders. Your fuel efficiency or gas mileage also takes a hit.

Note: Besides a fuel pump failure, a loose or damaged gas cap can allow gasoline vapors to escape from the gas tank, causing fuel to evaporate and a drop in overall fuel efficiency.

3. Engine Sputtering, Surging, or Jerking

A fuel pump malfunction, bad fuel pump relay, or clogged fuel filter can disrupt fuel flow. This leads to power fluctuations or engine sputtering — irregular and uneven bursts of power. Excess fuel delivery may result in sudden surges, whereas a reduced fuel supply may cause the vehicle’s engine to jerk or hesitate.

4. Engine Misfire or Stalling

A weak fuel pump can’t deliver sufficient fuel to the engine, resulting in a lean air-fuel mixture — too little gas in comparison to the amount of air. This fuel pump problem can lead to engine misfire or stalling, as there isn’t enough fuel for combustion.

Note: Sometimes, faulty spark plugs or spark plug wires can cause the vehicle’s engine to misfire.

5. Engine Overheating

The engine’s cooling system is designed to maintain the engine at the correct temperature. However, when your vehicle’s fuel pump goes bad, it can’t supply adequate fuel, leading to a lean air-fuel ratio. This imbalance forces the engine to work harder, generating more heat that can exceed the cooling system’s capacity.

6. Difficulty Starting the Vehicle

The engine relies on a precise air-fuel mixture for successful combustion. However, a malfunctioning fuel pump or fuel pump relay can upset this balance, causing too little or excess fuel flow. This imbalance hinders the engine’s ability to achieve proper combustion, making it challenging to start the car.

7. Failed Emissions Test

Incomplete combustion can result in higher levels of unburned hydrocarbons and carbon monoxide in the exhaust. These increased pollutants can lead to a failed emissions test.

When faced with a fuel pump issue, repair is rarely an option. Instead, the standard procedure is replacement. Let’s find out how it’s done.

How to Replace a Faulty Fuel Pump? (Step-By-Step)

Swapping out the fuel pump can be a tricky task. If you’re not confident, it’s advisable to entrust it to a skilled mechanic.

Here’s the procedure mechanics follow:

Before replacing the fuel pump, use a fuel pressure gauge or fuel pressure sensor to take a baseline pressure reading.

Next, run the engine until it stalls to relieve fuel system pressure.

Locate the fuel pump. Usually, it’s present inside the fuel tank or externally mounted.

Carefully disconnect the electrical connectors and the fuel line from the fuel pump and extract the old fuel pump assembly.

Replace the bad fuel pump with a new one, following the manufacturer’s guidelines, including torque specifications.

Reconnect electrical connectors and fuel line to the new fuel pump.

Reassemble any removed components, reconnect the battery, and get the fuel system ready by turning the ignition to the “on” position. Look out for leaks or strange noises.

Start the engine, monitor fuel pressure, and assess engine performance.

Use an OBD-II scanner to clear any stored trouble codes, especially if the Check Engine Light was previously illuminated.

Now that we’ve covered the fuel pump replacement procedure, let’s understand the estimated replacement costs.

How Much Does it Cost to Replace a Fuel Pump?

Replacing a bad fuel pump typically ranges between $400 to $800. However, the actual cost depends on your vehicle’s make and model, the type of fuel pump selected, and the labor rates in your area.

Coming up next are common fuel pump questions for a deeper understanding.

4 Fuel Pump Related FAQs

Here are the answers to some questions related to fuel pump maintenance and performance:

1. How Does a Fuel Pump Work?

The fuel pump extracts gasoline from the tank, filters it, and delivers it to the engine, where it enters the cylinders to help generate power.

In older vehicles, a mechanical fuel pump pushes fuel to the carburetor and then sprays it into the cylinders. In such systems, a mechanical fuel pressure regulator controls the fuel pressure delivered to the engine.

However, in modern vehicles equipped with electronic fuel injection, fuel delivery is handled by electric fuel pumps. These electric fuel pumps are typically located inside the gas tank or fuel tank and are more suited to systems needing a higher fuel pressure. An electric fuel pump is also considered safer because it’s surrounded by cooler gas and positioned farther away from the engine.

2. How Long Does a Fuel Pump Last?

On average, your vehicle’s fuel pump can last anywhere from 100,000 to 200,000 miles (160,000 to 320,000 kilometers) or more. The longevity depends on factors like usage patterns and maintenance practices.

3. Is it Safe to Drive With a Failing Fuel Pump?

Neglecting a known fuel pump problem endangers your safety and can lead to costly repairs. If you suspect a bad fuel pump, promptly arrange for inspection and replacement by a qualified mechanic.

4. How to Keep Your Fuel Pump in Good Shape?

Here are some tips to help you maintain your fuel pump:

Use high-quality fuel from reputable sources.

Stick to your vehicle’s maintenance schedule, including timely fuel filter, fuel injector, and fuel rail replacements.

Add fuel system cleaning additives every 3,000 miles to prevent contamination.

Address any fuel leaks or other signs of a bad fuel pump promptly.

Drive gently to reduce the strain on the fuel pump.

Wrapping Up

Fuel pump failure can lead to various engine performance issues, including knocking and stalling. Recognizing these signals is essential to prevent expensive repairs and maintain road safety.

What if you need a fuel pump replacement?
Fortunately, replacing a fuel pump becomes a breeze when you have AutoNation Mobile Service’s mobile mechanics at your service. Our expert technicians are available seven days a week, and we provide a 12-month, 12,000-mile warranty on all repairs.