So is it OK to just tap into the FSS power wire for the power to the electric fuel pump?
mostly answered.but here's the details.
no you cannot as stated.you need a relay.
splice into the FSS wire,and run this line into a standard 30 amp relay.place it on pin #86.
now ground the relay.pin #85.
ground the black negative wire coming from the pump as well (anywhere is fine.)
connect the red positive wire coming from your pump into the relay.pin #87.
now grab one of them inline fuse holders and hook it to a positive battery post.connect the other end (with an extension of wire of course) to your relay's last pin position.pin #30.
wire tie,loom etc all your lines.make nice an neat.
now place a 5 amp fuse into your fuse holder by your battery.
now when you go to turn on your key,she'll pump via a direct draw from your battery.