99 454 efi wiring harness woe's

[halcat]

I have a 454 with what appears to be a 99 6500 chevy efi injection system. The motor has a complete harness and was running when took out, and I took it out. The problem is putting it in an other rig, I don't understand how to wire it up. The harness only has four wires leaving the harness, pink, orange, brown and I forgot the other color. Also they are only 16 or 18 ga. Wires. I know one is constant hot, ignition hot, fuel pump, ???. How does the engine and fuel pump get the fire they need with this small wires? What am I missing? Relays? I need this running, but I'm afraid to connect anything for fear on cooking the computer. The harness has been cut down but has all the censors connected. Can I send it to someone and get it labeled? I took it out my self and have the rig it came out of but can't tell anything about the wiring. There were only these four small wires connected to the other buggy. Help somebody.