How to Tell If a Fuel Pump Is Bad?

Your car may not start if it has a bad fuel pump.

If your vehicle will not start up or run, or is running very badly and acting like it is out of gas when you know it isn't, there is a chance that your fuel pump has stopped working properly. When your fuel pump is malfunctioning, it can completely stop your vehicle from operating. It may also cause your car to perform very poorly while driven, and your car may stall frequently. If you believe that your fuel pump is malfunctioning, you should repair it immediately. There are several ways to tell if your fuel pump is the culprit for your car's problems.

Things You'll Need

• Voltage meter

Instructions

1. Try to start your car. If it attempts to start but never actually fires up, there is a reasonably good chance that a bad fuel pump may be the reason why. Because your fuel pump's job is to provide fuel to the motor, when it malfunctions your car will not get the proper amount of fuel.

2. Listen for the fuel pump: Turn your car's key to the "start" or "on" position, but do not actually try to turn the car over. Make sure your radio is off and you are in a quiet environment--if cars are passing by nearby, you might not hear what you're listening for. Listen carefully for a electronic sounding whining, whirring or humming noise that will come from the area around your vehicle's fuel tank. If you do not hear anything, chances are that your fuel pump is not coming on the way it is supposed to.

3. Pay attention to how the car is running. Your fuel pump may still be the problem even if your car will start. In the event that your car does start but acts like it is almost out of gas even though you know it has plenty, your fuel pump may be the cause. The fuel pump's job is to deliver fuel to the vehicle's motor. If it is not delivering fuel, or if it is delivering too much fuel, too little fuel or fuel in spurts, your car is going to cough, spit, sputter and stall as if it were out of gas.

4. Check the power to your fuel pump by connecting a voltage meter to the vehicle's fuel pump wiring. How the voltage meter will connect depends on your type of vehicle. Turn the car on, but do not attempt to start it. If your fuel pump is not getting any power, than the problem is likely to be in your wiring and not with the pump itself. If your fuel pump is getting plenty of steady power but can not be heard turning on, then chances are it is the fuel pump itself that is broken.

Tips & Warnings

• You should consider having your car diagnosed by a certified mechanic before you begin replacing parts. Working with a vehicle's fuel and electric systems can be dangerous.

References

• AllPar Repairs: Electronic Fuel Pump Problems and Replacement