I have and 89 gta 77,000 miles it cranks but wont start it is getting spark and the rail has fuel, no lights on the dash come on when you turn the key forward except the security light and the seatbelt light which turn off after a few seconds leaving no lights on the dash on . when the terminal is jumped it also does nothing. I just replaced the computer about a month and a half ago it looks as if its dumped out again. Any feed back on what you might think would be very helpfull here.

 

i don't know if this will help but when my 87 GTA did about the same thing it was because my ignition module got covered in oil. The car would just turn over and over and over. I put a new coil in the car and it started right up then ran for a bit then wouldn't run anymore. Once I found the ignition module covered in oil I cleaned it off and the car ran great from then on.

 

I would guess you are having a VATS problem.