It is not recommended. When the ignition is on the on board computers are active, and it is never a good idea to remove power from a computer while it is active.
Numerouse possibiities, bad gas, bad carburetor, bad spark plugs, bad spark plug wires, bad ignition coil, bad battery, bad ignition swithc, etc..
Put Key in ignition and turn it a bit.
It shouldn't. When the engine is running, electricity is supplied by the alternator, not the battery. If the engine dies when the battery is disconnected, the battery and/or some related part (such as the voltage regulator) is bad.
You will destroy the voltage regulator if you unplug the battery while it is running, then you will have to replace the alternator anyways.
Start the car, unplug the battery the alternater should power the car. If it dies the alternator is bad. You can also get it checked at any parts store.
The neutral safety switch could be bad or the ignition switch is bad .
Possibly dead battery, defective starter, corroded battery cables, or bad ignition switch.
Disconnect the negative cable first.
I would suspect you have an ignition switch going bad, a starter solenoid that may be going bad or more than likely corroded or loose battery cable connections. Check the battery post connections first.
Unplug the fuse labeled "fuel pump"
unplug your car battery
make sure the car is in park. if it is then you might have a bad battery. charge the battery and get it checked. you might need a new one.