12 Bad, failing, & weak fuel pump symptoms

The fuel pump is probably the most important part of your vehicle. Its function is to take gas from the tank and send it to the engine. It allows your car to start and run. Because it is such an important part, fuel pumps should last you for at least 100,000 miles.

If you have already exceeded this mark, there is a high chance of the fuel pump failing. When that happens, there are specific symptoms you can look for and take the necessary action to replace this component. The fuel delivery system is complex, and such an important part has to be highly valued.

Holley Blue fuel pump

For modern cars, this part is considered to be their heart. Once this pump fails, the entire vehicle will stop running, and you might also have trouble starting it up again. This article will look at 12 bad, failing & weak fuel pump symptoms so you can make troubleshooting easier. 

What does a fuel pump do?

This part sends gas directly to the engine, which makes it a vital part of your vehicle. This process is simple but essential. The gasoline will pass through a fuel filter to reach the injectors and finish by combusting inside the cylinders. 

Without this pump, fuel would have no way to reach the engine, and the pistons would have difficulty delivering power. In some older vehicles, mechanical fuel pumps use complex diaphragms to transport the fuel to the engine. 

Modern cars have electric fuel pumps mounted inside the gas tank. These ones are also safer because they reduce fire risk. Since they are installed far from the engine, they often work independently. 

If this part is failing, it is crucial to change it as soon as possible, as your vehicle might represent a real danger for other drivers. Your car will not work properly without this component.

fuel pump

How to tell if the fuel pump is bad: Signs to look out for

There are several signs and symptoms that will tell you if this part is bad or failing. We found the most common 12 ones, so pay attention and notice if you can identify some of them in your vehicle.

  1. The check engine light comes on.

This light will appear on your dashboard once you have fuel pump issues. Most likely, your car has already started running weirdly. It lacks the smoothness you were used to. 

Use the check engine light as a final confirmation that something is wrong with the component. A specialized mechanic will be able to diagnose your vehicle and recommend replacement parts.

  1. Increased fuel consumption

When this component is failing, the engine might consume more fuel. You should notice this after driving for a while. You will know the difference between your average consumption and the new one. 

In this case, you might want to check the entire fuel system. Take your car to an auto repair shop and have the experts take a look at it. 

Fuel pump for Ford
  1. The car struggles to climb a hill.

If you live in an area with hills, you are most likely used to having your car climb them effortlessly. When this part is failing, the entire performance of your car is reduced. You will notice this, especially when you are driving uphill.

  1. Reduced power

Because there is not enough gas supplied to the engine, the power will be reduced. It means you might lose the ability to reach and maintain a stable high speed. On a highway, this can be dangerous.

Pull over to the side and call for help, as your vehicle is now a danger to other drivers. 

  1. Engine speed fluctuates

Because the gas delivery is uneven, the performance of your engine will fluctuate. The car will want to accelerate and slow down shortly after while constantly repeating this cycle. On a highway, it can be extremely dangerous.

  1. Acceleration is hesitant

Under normal circumstances, your car should be able to accelerate quickly from a full stop. An instant response is necessary, especially on a busy street or when you merge into traffic. 

But if your fuel pump is failing, you might experience a delayed response when you step on the gas. 

  1. The engine is misfiring.

Often, you will feel misfires rather than hear them. They will feel like your car is bumping a lot, and it is clearly an indication that there is something wrong. Misfires will eventually damage your engine, so you should replace this part as soon as possible.

Fuel pump for Ford Diesel
  1. Rough running at low speed

If rough running occurs only once, it is not something to worry about. But if this problem occurs frequently, you should start investigating and consider this part as a possible cause.

  1. The engine suddenly stalls.

Sometimes your engine suddenly stops, and you can’t explain why. It can be annoying and incredibly dangerous if it happens on the road. You should fix this problem as soon as possible.

  1. You can’t start the car.

As you turn the key or push the start button, nothing happens. Sometimes cranking the engine takes longer than you expected. In this case, a starting failure clearly indicates a failing fuel pump. 

2011-2016 Duramax Fuel Pump
  1. Overheating engine

Your car’s engine might overheat for various reasons, and a malfunctioning fuel pump is one of them. It happens because the bad pump incorrectly delivers gas to the engine, causing it to run too hot.

  1. Low fuel pressure

Test your fuel pressure to determine the cause of a failing pump. You can do this with a pressure gauge found at any auto shop. Find the recommended pressure of your vehicle in its owner manual. Compare the result with the indication provided by the manufacturer. 

Bad fuel pump relay symptoms

Cp4 Fuel Pump Off 2011 Duramax

Many processes take place when you turn the key in your car. One of them is the vehicle’s ECM sending a signal to this part, commanding it to put a specific amount of gas to start your engine. It is done with the help of the fuel pump relay.

When this relay gets powered, it sends the signal to the pump. When it malfunctions, it automatically switches off. This component cannot work properly. There are 5 symptoms you should look for in a bad pump relay, and they are:

  • The engine is stalling
  • There is no noise from this part
  • Check engine light comes on the dashboard
  • You cannot start the vehicle
  • Rough acceleration

What happens when the fuel pump goes out while driving?

If this part goes out while driving, the car will most likely turn off. You will have to pull over to the side of the road and call a car towing service. If you have an older diesel engine, you can still drive a few miles with a faulty system, but it might be difficult. 

Rolling at a low speed and avoiding steep hills might let you reach the next town. But fuel-injected gasoline engines will stop functioning entirely, and you might have to spend the night on the highway. Without gas running through them, these engines cannot function. 

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

Bmw n54 high pressure fuel pump

When this part goes out, the car will show various signs. For example, a damaged fuel pump might make a loud noise coming from the gas tank. But this sound can also occur if you are low on fuel or the fuel itself is contaminated. 

Additionally, you might struggle to start your car. This part cannot push enough gas to the engine, preventing it from starting. You will notice a different performance if you still manage to start it. Your engine will sputter and stall. 

What causes the fuel pump to go bad?

There are many causes of a bad pump. The most common ones include contamination, overheating, and the part itself wearing out over time. Another cause is rust, debris, and dirt particles that clog up your pump filter. With time, it is making the pump harder to operate efficiently.

This part has many components inside, and these particles will stress and accelerate their wear. Next time you refuel your vehicle, make sure the gas pump is pushing no particles in your car’s tank to avoid a clogged pump.  

APR high pressure fuel pump with parts

How to check if a fuel pump is bad

You can start by checking the relay. In older fuel systems, the engine doesn’t control this component directly. Instead, it uses a relay. If this relay is broken, this part will stop working. 

If the relay is functional, check the fuel pressure regulator. On a continuous system, disconnect the attached vacuum hose and see if the pressure increases on the regulator. The regulator is faulty if the pressure does not increase.

Fuel pumps have an external filter that is very easy to install. Instead of testing it, you should install a new one and see if your problem is fixed. Before replacing the filter, relieve the fuel system pressure while wearing adequate safety equipment.

Bmw fuel pump

What would cause a new fuel pump to go bad?

Gas contamination is one of the most common causes of fuel pump failure. With corrosion, debris, and moisture, fuel is ruined and will bring contaminants into the tank. These contaminants will eventually clog essential components, filters, or even the pump itself.

This blockage will stop the fuel flow, making it difficult for your vehicle to accelerate or run properly. At the same time, electrical faults are also responsible for pump failures. Rusted connectors or melted wirings can stop the pump from functioning properly. 

FAQ

Make sure to check out our article on catalytic converters.

How long does a fuel pump last?

It is not recommended to replace this component if it is functioning properly. Still, you can install a new one if you are currently performing a service on your car that involves removing the gas tank. 

Replacing this part will benefit you if it has been running for more than 100,000 miles. Not only will it save you money with further costs and repairs, but it will also save you time. You don’t want this component to fail suddenly when you are cruising on the highway or on a journey with your family with a long way to go to the destination. 

However, you should replace this part as soon as possible if you notice the pump surging and not delivering enough gas. A qualified mechanic should have a look at your car, and they will also help you with replacing the faulty part. 

Can you still drive with a bad fuel pump?

It is extremely dangerous to operate a vehicle with a bad fuel pump. A faulty pump could cause an unexpected loss of power or even completely shut down your vehicle. If these occur while you are on the highway, your car becomes a significant danger to other drivers.

A bad fuel pump might also cause the engine to overheat. When this happens, the pump will incorrectly deliver gas to the engine. It might turn off while you are on the road. In such a situation, you must pull over to the side of the road and wait for help. 

Where is the fuel pump located?

While fuel pumps are essential and well-known, not everyone knows where they are located in a vehicle. This part is working hard under difficult conditions and is essential for the optimal performance of your car.

In modern vehicles, this part is located inside the gas tank. If you want to replace it, a special access port is fitted on the trunk floor or under the rear seat. On diesel-fueled engines, there are often 2 pumps installed.

A lift pump is fitted inside the fuel tank while a high-pressure pump is installed in the engine. If this part fails, you might need to replace both of them. 

Can a fuel pump fail suddenly?

Sometimes these failures can be sudden and unpredictable. There are a few symptoms that warn you when the pump is failing. Be advised that the risk of pump failure is higher if your vehicle has high mileage. 

This pump is considered the heart of the fuel system. If this part stops working, the fuel flow is cut, and the engine dies. You cannot drive a car with a faulty pump, as it won’t power up the engine. 

You should check with a mechanic and ensure the problem is related to this component. Often, replacing this part does not fix the problem because the problem might be related to something else. 

What does a fuel pump sound like?

If this part is making a low humming sound, then there is nothing to worry about. The pump is supposed to make this noise, and most people are used to it. An electric motor generates this sound, which will always make a soft hum when your engine is turned on.

But if you notice your fuel pump whining or buzzing, then there is something wrong with the pump. Along with other symptoms, this odd sound is a clear warning sign that this component is failing. You should replace it as soon as possible. 

Additionally, you can take your car to an auto repair shop and have a skilled mechanic look at it. Diagnosing and repairing your vehicle is easy for them, and they might even teach you some things about the fuel system. 

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