ok heres what the deal is. I will turn my car all the way to the dashes before actual ignition and everything turn on like normal and then i try to start my car and my motor wont even crank like it sounds like it'll just blow a fuse or something but I am able to jump my car without a problem and it'll run until i turn my car off? Bad alternator? PLEASE HELP!!

PS. Just had battery and alt. checked both are good. Lookin at a short in the sytem prolly.