What is the 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.
A fuel pump's lifespan typically lasts for about 100,000 miles, but could be more or less. Usually, a fuel pump that isn’t working will produce one or more of the following symptoms that alert the driver of a potential issue.
1. Fuel Tank Making a Whining Noise
One of the first symptoms of a bad 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 bad fuel pump. There may not be enough fuel, a damaged pump, or contaminated fuel inside the system.
2. Vehicle is Difficult to Start or Won’t Start
Another symptom commonly associated with a bad fuel pump is difficulty starting your vehicle. 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 the vehicle may not start at all.
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 sputters 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. Vehicle 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. Vehicle Loses Power Under Stress
Another symptom 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. Vehicle Surging or Jerking
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.
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 to need to replace the fuel pump. Another reason fuel pumps fail is regularly keeping less than 1/4 of a tank of fuel in your car.Fuel pump replacements can be complex, so it’s always best to contact a mechanic to inspect your vehicle and perform a fuel pump replacement if you are uncomfortable doing it yourself. If you choose to replace the fuel pump yourself, you want to make sure you replace it with a quality fuel pump to ensure longevity in your vehicle. If your vehicle is displaying any of the symptoms above, or you suspect your fuel pump may be having an issue, contact YourMechanic to have the vehicle inspected by a mobile mechanic to determine if the fuel pump should be replaced.
