Mobilwash99

I have a 2000 Chevy Astro Van Vortec V6 with 210,000 miles the engine is bad. I purchased a 2003 GMC Safari Vortec V6 with 19,000 miles I swapped the complete engine and transmission from the 2003 GMC into my 2000 Chevy. BTW the engine in the wrecked GMC did start and run. I also swapped the engine room harness and ECM the main plug looked the same and plugged right into the plug on the firewall by the battery I did notice that there was one extra terminal on the harness on my 2000 Chevy that the GMC plug did not have. The engine turns over but will not start it appears that the fuel pump is not powering up. Im hopeing that I will not have to swap the intake maifold and exhaust maifold as well as the old harness from the old motor. I dont have access to accurate wiring diagrams or pin identificaion for the plug to ID the wire that im missing and determine what it actually controls.. Any help would be great also just a note I have 30 years experance as Tech for Toyota and UPS have been out of it for the past 6 years