Fuel injectors work to monitor the amount of fuel that enters the intake of a vehicle. The computer in your vehicle, also known as your PCM or power train control module, gets input from the engine sensors. It then sends an electrical signal to the fuel injector that tells it how long to stay open and how much fuel to allow to pass. Fuel injectors do not break, but can go bad. There are some ways to determine if your fuel injector is faulty.
Listen and feel for symptoms of fuel injector failure. The car will misfire and begin to hesitate. It will have a rough idle, not smoothly accelerate and may suffer from power. It may fail emissions testing in some cases. While these problems also be signs of other issues, they also are the first way to alert you to a possible fuel injection problem.
Check your trouble codes. The check engine light will come on when your fuel injectors are bad. You can test your car with an on-board diagnostic (OBD) to find the codes. An OBD can be purchased at an auto parts store. Plug it into your car. Consult your owner's manual for the car's plug location. It is typically found on the driver's side, underneath the steering column. Once you have the code, consult the dealership or the auto parts store. They can inform you on what the code indicates.
Listen to your fuel injectors with a stethoscope. Consult your owner's manual to determine where the injectors are located in your car. Turn the engine on and touch the stethoscope to each injector. Listen for a series of clicks. The clicks indicate that the valve is opening and closing with each cycle and is working properly. If you do not hear the clicks, the injectors have gone bad.
Remove the fuel injectors to check for leaks. Place a paper towel under the injectors and turn the ignition to the "ON" position, but do not start the car. Check the paper towel after a few minutes. If there is fuel, then your injectors are leaking.