If the pump is a bit low it will make a vacuum sound plus if the plug is removed with the cylinders extended, it will too. I suggest for you to assemble the system, fill it, and slowly operate the top. You can do that with short activations of the switch. This should allow you to see if all goes well. I do not think any of my verts have operated in perfect unison. Might look at a new one at a dealer just to see.
Panama City, Fl.
I wake up in the morning with nothing to do and by supper time, I have half of it done.
2000 Lightning, s/c, tuned, Basanni, built tranny
Sold them all.....
Previous Mustangs:4 - '66 Coupes(silver/blue/grey/red) '87 GT HO, '00/'02/'07 GT Vert(red)(grey)(black), '68 Coupe, '11 GT/CS, 08 GT Vert