vacuum lines and code

['86_150]

on my 1990 f150 with the 5.0 i just replaced the head gaskets and i was positive i marked all of the vac lines but i guess i missed one so i know the long vacuum line on the pass side goes to the egr but where does the shorter line that comes out of the harness on the front of the engine go? and i pulled this code i forgot the number but the book said it was the fuel pump secondary circuit failure what does this mean? any help is appreciated thanks much.

[EPNCSU2006]

Do you have any pictures of the vacuum line and its location? I would reset the fuel pump code (just pull the jumper wire while the codes are blinking) and see if it comes back. If it does and the fuel pumps still work, I'd just ignore it.