What he said. Make very sure what that wire goes to. From the factory. Black wires are nearly always grounds. If someone added a wire that can complicate things allot.
If you are trying to run the fan motor directly from the fuse block... good luck. The radiator fan draws a rather huge amount of current and doesn't run off the fuse block. The E Fan fuse only protects the control circuit side of the relay and runs the small auxilary fan on 85-87 V6 models.
The fan is covered partly in one of my cave articles. Start there.
Also keep in mind... If your cooling plumbing is working properly... In normal operation the fan won't turn on very often even in hot weather. You have to sit still quite a while to get it running with an L4, not quite so long on a V6.
The only thing George Orwell got wrong was the year.
The Ogre's Fiero Cave (It's also at the top of every forum page...)