Note those yellow wire are hot all the time and not controlled by the Ignition switch.
Nether of the those yellow wires sends power to the Fuel pump circuit.

 

Bill, you are correct about the yellow being hot all the time, I figured that out this morning after your caution about overloading the ignition. Do you have another recommendation for a power pick-up? Thanks.

 

You are talking about a fairly a large current. I do not think there is any source inside the van to tap.

I do not know why you are going through all of this. It is not necessary and could be very dangerous as the fuel pump may not turn off if you are in an accident. The computer stops the fuel pump one second after the engine quits running even if the key is still on.

You talked about the fuse relay box having a problem. I have never seen a problem with the under side of a fuse relay box. Sometime someone will stick something in the fuse or relay sockets and spread them. This will make a loose connection and cause heat and melt the socket some but other than that the fuse relay box should be fine.

Grounding pin #6 of your self-test plug and turning on the key should close the fuel pump relay. Then using a loading test light you should be able to trace to the problem item. It is a very simple fuel control system.