PCB is short for Printed Circuit board. IE, the circuit board inside your ECU. Don't worry about smelling it. It's toast. There are fusible links under the hood that should blow, but I think they are way more powerful than that ECU circuit board is. Generally, if something inside the ECU shorts out bad enough to do that, a fuse is only going to prevent it from melting, you'll still have to replace it. And the reason your fuel pump is still going is probably because your pump was running when your ECU went tits up, so the switch inside the ECU that turns on the pump got stuck in the on position. (Best guess..)
There are probably 10-15 88 Sentra's at my local junkyard, if you want me to go fetch you a computer, lemme know, and I'll find out how much they want for one.
