I have a 1994 Dodge Ram 1500 2WD with the 318 (5

I can't read that huge sentence properly with no punctuation. You said you "changed the motor and it still comes on". So is it running or isn't it? Are you aware the pump should only run for one second after turning on the ignition switch, then again during engine cranking? Do you have the manufacturer's service manual? If not, I can try to find one. "Burned out wires" can mean a lot of different things. What else doesn't work?

Dandy.

Black / white and dark blue are for the fuel gauge sending unit.

Dark green / black is the 12 volt feed to the pump.

Black is the ground wire for the pump. It is spliced in with the ground wires for the tail lights, license lights and backup lights, but they neglected to show where that ground attaches to the body. If all the rear lights work, you can safely attach that black wire to the body. If any of the rear lights don't work or if they work incorrectly, I'll try to figure out where that splice is located. That, and the ground connection, would be the two logical places to find a problem.

I can't determine where the ground wire is bolted to. I suspect it goes to the frame because the box is on rubber isolators, but then again, the lights normally ground to the box, ... So there would have to be a ground strap somewhere.

The fastest for now is to determine which you're missing, 12 volts, ground, or both. Use an ohm meter to measure the resistance to the frame on that ground wire. It should be real low, as in a couple of ohms. If you have that, test for 12 volts on the dark green / black wire. A lot of digital meters don't respond fast enough to catch that during the first second so a test light might be more accurate.