I just got my '87 Firebird V6 back from the mechanic's shop. It went it for work because it was blowing the 20A underhood fuse that was connected to the fuel pump relay. The shop diagnosed it as a fuel pump failure and replaced the fuel pump. In the course of the repairs, the shop thoroughly tested my car before releasing it to me. It stalled on them a few times, repeating the same problem that caused me to bring it in. (Turn key to ON, no SES bulb check, crank, but no start condition, 20A fuel pump relay fuse blown as soon as key was turned to ON.) One of the mechanics spent some time tracing the wiring, and came to the conclusion that I either had a bad ECM or a wiring fault. He pulled out my ECM, which had two bent pins, and replaced it with the ECM from his 1987 Chevy Camaro V6 w/ 4-spd auto trans, which he said was a direct swap. After we swapped in his ECM, the problem was still there. Every now and then, the car will run, but it will die randomly. Lately, I haven't been able to get it to run at all. I have attached two pictures from the underhood view, one showing the 20A fuse at fault, which is fed by a red and orange wire, and another showing where that orange wire goes, to the fuel pump relay. When my mechanic spliced in another wire, as you can see by the blue connectors, and turned the ignition ON, the SES light came on, but the wire that he spliced in began to smoke. We shut it down right then, and he informed me that I have a "dead short" somewhere. Oh yes - Before he spliced that orange wire, he used a jumper in place of that 20A fuse to see what would happen. After 5 to 10 seconds, the jumper became too hot to touch, indicating a very large current draw.

Does anyone have any better ideas, or can anyone please describe, in detail, where the short is most likely to be, and how to repair it? (I have minimal auto wiring knowledge, but can do basic stuff if I take it slow & steady.)

Thanks!