My car will start 6 straight times, but on the seventh time, I hear 2 spark plugs fire, then I hear nothing. The car won't start.  1998 Kia Sephia, 55,000 miles.

Then, I turn the key to the off position, next I turn the key, on again, the car  started right up for another 6-7 times without a problem. 

The first starter stopped working, 4 months after I bought the car.  Before the starter went bad, I took out the starter, my buddy and I  hooked the starter up to a battery.  The pinon  gear seemed to working fine.  I installed the starter back into the car again.  I turned on the key and the car started right up.  I turned the key off, after 3 mintues.  After that, I tried to start the car again, the car would never start again!  What is going on with my starter?