91 240sx not starting HELP!!!!!!

[s13kyd]

i have a 91 240sx not starting battery is fully charged car was working perfectly fine 8 hours ago before i went to work i came home to start it and nothing everything turns on but the car wont turn over.

couple of my buddys came by and we push started the car and it fired right up then my buddy told me to turn the car off so i did and it didnt want to turn back on so we once again push started it fired right up again i have a brand new bosche starter and ign switch so i dont know whats going on i really dont know what to do any ideas

thanks....