Symptoms of a Bad or Failing Fuel Pump

Virtually all modern vehicles with internal combustion engines come equipped with fuel pumps. The fuel pump is responsible for delivering fuel from the gas tank to the engine at the appropriate pressure required for performance demands. When the 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. 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. Usually, a bad or failing fuel pump will produce one or more of the following 8 symptoms that alert the driver of a potential issue.

1. Whining Noise From the Fuel Tank

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. Difficulty Starting

Another symptom commonly associated with a problematic fuel pump is difficulty starting. Because fuel pumps constantly run whenever the ignition is turned on, they can eventually wear out and weaken over time. A weak fuel pump may still pump fuel, but the vehicle may experience difficulty starting from the lack of pressure. A weakened fuel pump can cause the vehicle to take more cranks to start than normal, and in more serious cases may even cause the vehicle to require multiple turns of the key before it will start.

3. Engine Sputtering

One of the surest indicators of a faulty fuel pump is a sputtering engine — 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. Stalling at High Temperatures

Stalling can happen because of multiple problems within a vehicle but pay attention when it happens frequently at high temperatures shown on the car’s thermometer. A rising temperature paired with stalling often indicates a problem with the fuel pump motor. If stalling continues to occur with an increasing temperature gauge, it could indicate the fuel pump’s deterioration and need for replacement.

5. 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.

6. Car Surging

Irregular resistance inside the fuel pump motor may cause vehicle surging, and indicates a fuel pump in need of 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.

7. Low Gas Mileage

If it seems like you’re filling up your car more than usual, it may be because of an issue within the fuel pump. A valve within the fuel pump may not be opening, causing more fuel than necessary to pour into the engine system. Excess fuel in the engine does not get stored or used.

8. Car Will Not Start

Another more serious symptom of an issue with the fuel pump is a no-start condition. If the fuel pump fails completely — to the point of not being able to provide enough fuel for the engine to run, the vehicle will refuse to start. The engine will still crank when the key is turned, but it will be unable to start due to the lack of fuel. A no-start situation can also be caused by a variety of other issues, so having the vehicle properly diagnosed is highly recommended.

Fuel pumps are found on virtually all internal combustion engine-equipped vehicles in one form or another. Most fuel pumps are built to last. However, as the vehicle reaches high mileage, it is not uncommon for fuel pumps to require replacement. Another reason fuel pumps fail is regularly keeping less than 1/4 of a tank of fuel in your car. If your vehicle is displaying any of the symptoms above, or you suspect your fuel pump may be having an issue, have the vehicle inspected by a professional technician to determine if the pump should be replaced.


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