I had a broken wire in my steering column that caused a no read from the resistor in the key. I used a Jet Perfomance "bypass VATS" chip to bypass the problem and it worked fine for about a week. Then it stopped running and was acting like the VATS was disabling the ECM again. I replaced the wire and still wouldnt fire. Replaced the ECM (used) and PROM (new) and still wouldnt fire. Then I replaced the passkey box with a key and matching box from a running car. Still wont start. Then I bypassed the starter portion of the VATS and ran the wire to the neutral safety switch and the car cranks but injectors wont fire. The engine starts with prime but injectors arent firing. I dont know what esle to try and I hate to take it to the dealer for service. Anyone can help me please respond. Thank you

 

The car is a 1991 Z28 and I sent the bypass chip back to Jet and they replaced it but it didnt help. Any help is really appreciated. Thank you

 

Take out you ignition module and have it tested. With all of the electronic work you have done you could have easily fried it. The ignition module gives the ECM the reference for pulsing injectors.