s3performance

I purchased a 86 rx7 with no motor for $200. I baught a motor, wiring harness, and ecu all out of the same car and installed it. I then hooked up the battery and nothing sparked or smoked so i tried to start it but it would not fire. Checked the fuses and one was completely melted so replaced it and it fired up and then died after about 8 seconds. So I then went on and found a empty plug in and tried it with the test light and i heard the fuel pump go but there is no other empty plug in that it will fit. So i started it with the test light and it ran and then still died so i kept starting it and trying different things and still nothing but one time after it died something sparked and now i got nothing it wont even turn over. I checked all the fuses and ripped apart the the whole harness and checked for burns and so on and found nothing it was all fine i even ohmed them all to see if anything was going through the wires and all were fine. If anyone can help me out in any way that would be great or if someone has another harness that i could buy that would also be great and i will check the classifieds. Thanks, Jeff