LG-IH fuse has “no power” or not enough

Ok, this is the third time I’ve been left stranded because of this. The fuse does NOT blow, but I get “no power” to this one fuse, causing my NEW alternator not to charge, which means a quick loss of fuel pressure. I also have a new battery. Since I’ve got it, the battery light is on unless rpm’s are above 1500. Whether or not the battery light is on or not, I have 10.5-11 volts. Starts fine, just won’t last. Once again, the fuse is not blowing. I was thinking it could be a yellow wire that ran from it to the alternator, but when I went and looked, there was no yellow wire(the socket attached to the passenger side of the fuse box). I say it gets “no power” but I guess I should say not enough. The blinkers still work, and when I take the fuse out, they do not, so either it has power and is being funky, which I suspect is what it is, or it just uses that fuse to ground something out for them. I NEED my truck very soon, but I can’t run it like this. HELP!