if the motor cranks when you turn the key it is not the starter because in order for the engine to crank the starter must be turning the motor. it could be electrical or fuel related or sensor related, ect. depending on the model and year you could check for fault codes ie:OBD 1 or OBD 2
starters bad
polar car starter programing
It's broken!
Either your starter solenoid, if not check the neutral safety or clutch safety switch.
solenod
It may be possessed by a demon! OR... Does it have a remote car starter installed? It may be faulty. The ignition switch may be bad. The key goes into the ignition lock. There is usually a rod that goes down to the electrical switch on the steering column. check the electrical switch.
The starter is what helps for only you to be able you use your car. Usually the starter is calibrated only to work with your key, and will send electrical signals that cause your car to start.
The starter on a car requires a lot of electrical current to rotate the engine fast enough for it to start. When the car's battery doesn't have enough electricity to do this a battery from another car or another source of electrical current can be supplied (jumpered) to the car to "jump start" it.
There is an electrical problem between the starter switch and the starter solenoid. The most likely cause is a loose connection at the solenoid or the fusable link has melted.
The Model T Ford which switched to electrical start in 1919.
Sounds to me that the starter motor is in electrical short that is discharging the battery. I would take the starter motor to the electrical shop to be tested (or the car and ask them to check the starter).
In the car electrical system, the starter motor is the first stop after the battery, so the problem has to be with that.
In this case, the starter was the problem after 55K miles. While driving on freeway, the instrument cluster of lights flashed momentarily and then the car went dead. After coasting to the side of road, the electrical system worked fine, but the car wouldn't start. Not sure why a bad starter caused the car to go dead while driving. After inspecting and cleaning all electrical connections from the battery to the starter, and checking all related fuses and relays, I came to the conclusion that the starter motor must have gone bad. I replaced the starter motor and the car started right up. See "How to replace the starter motor."
polar car starter programing
The 'starter' actually turns the flywheel, enabling the car engine to start. The 'alternator' supplies AC & DC current to the electrical components of the engine and vehicle.
When the key is turned on, it closes an electrical circuit. That closes another electrical circuit which makes and electromagnet work. The electromagnet closes a circuit between the battery and the starter. That starts the car. So the key does not actually do any work to start the car but it tells the various circuits to get busy and start the car.
No
It's broken!