7 Indications of a Bad Fuel Pump and How to Fix Them

How often do you think about your fuel pump? Fuel pumps inject gasoline from the fuel tank to the engine in a majority of cars and trucks. Your vehicle can’t function without a working fuel pump, and if it stops working, then your car stops driving. Almost all modern vehicles have electric fuel pumps mounted on their fuel tanks, and others have inline or mechanical pumps. Because the fuel pump is responsible for supplying the engine with fuel, any issues will lead to major performance problems and potentially expensive auto repairs. Eventually, most fuel pumps in vehicles will need to be replaced.

How Do You Know If Your Fuel Pump Is Bad?

A pump that is damaged or failing will produce some very obvious signs, such as engine sputtering, decreased fuel pressure, or loss of power. Sometimes you will also notice an inability to accelerate, a decrease in gas mileage, and the vehicle outright refusing to start.

1. Engine Sputtering

When you are driving consistently at high speeds, you may notice a sputtering engine, which is caused by the failing fuel pump. If your vehicle sputters suddenly and then chugs back to regular performance, this is a good indicator. Sputtering happens when the pump struggles to supply a constant stream of fuel to the engine.

2. Fuel Tank Noise

A damaged fuel pump might make a loud, whining sound that you’ll hear off your gas tank. The pump might also make noise if you’re low on fuel or if the tank is contaminated. The normal noise that your fuel tank makes is a low hum, so if you hear anything different, there might be an issue.

3. Loss In Fuel Pressure

Low fuel pressure can often lead to low acceleration, rough idle, engine stalls, and more problems. If your check engine light is on and your car is stalling, you probably have a fuel pump failure. 

4. Loss of Power

If you’re climbing a hill or hauling cargo and you lose overall power, you might have a fuel pump issue. When your vehicle is performing stressful tasks, the pump might be too weak to keep up with the taxing demands of driving. Any loss of vehicle power during acceleration might be an indicator of a fuel pump issue.

5. Inability To Accelerate

Some irregular resistance within the fuel pump motor can often lead to your car slowing down, or just being unable to accelerate at all. A failure to accelerate is a pretty good sign that your fuel pump needs inspection, similar to the loss of engine power.

6. Decreased Gas Mileage

If you notice a significant dip in your gas mileage, there could be a few issues under the hood. Fuel pumps have a relief valve that will allow more fuel than necessary to flow into the engine system if it fails to open, and if you’re refueling your car more often than you’re used to, then it might be a fuel pump issue. This alone is a good reason to get your fuel pump replaced, as your car chugging gas will be more expensive in the long run.

7. Engine Not Starting At All

Ignoring any of the above problems will inevitably lead to this. If the fuel pump completely malfunctions, then fuel won’t be able to reach the engine and your car won’t be able to start. There could be other factors, but diagnosing a fuel pump issue is typically the result of any of the previous issues.

How to Fix Damaged Fuel Pump

Your fuel pump does a lot for your car, and if it goes out, you’ll need to take care of it. It’s possible to fix it or even replace it yourself, as it can sometimes be a costly repair. If the fuel pump is failing on your main vehicle, this can be agonizing and frustrating, and you’ll want to get it fixed as soon as possible. If you feel like handling it yourself, consult the steps below.

  1. Disconnect the negative battery cable in your engine.
  2. With a safe workspace at hand and your car parked on a level surface, jack it up or place it on a lift to access the underside of your vehicle.
  3. Relieve the fuel system pressure (this is different depending on the make and model of your vehicle, and you’ll want to Google this or consult your service manual).
  4. Disconnect the filler neck from the fuel tank.
  5. Support the fuel tank via the jack and block of wood.
  6. Remove the bolts from the straps that hold the fuel tank in the vehicle.
  7. Very carefully disconnect all wiring connections, fuel lines, and vent hoses on the top of the tank before lowering the tank (as this will probably spill gasoline and oil, be careful).
  8. Once you release the connections, use the jack to lower the tank out of the car.
  9. Clean the top of the tank around the existing fuel pump assembly to prevent any debris from falling into the tank.
  10. Refer to your service manual for all instructions on removing the fuel pump assembly from the tank, which typically includes removing a plate held in with screws or bolts.
  11. Install the new pump in the opposite order you removed the old one (Reconnect the fuel lines, wiring connections, vent tubes, and battery cable).  Don’t forget to check the oil pressure in case you have spilled more of it.
  12. Fill the tank with gas and take your vehicle for a drive to ensure you’ve properly replaced the fuel pump and everything is working.

If you find this process intimidating, reach out to your local auto parts store, dealership, or auto mechanic and have them help you or take care of the fuel pump issue entirely. Once you fix or replace your fuel pump, your vehicle should enjoy many more years of service.