Any suggestions on where to start looking. When I put a fuse in the horn works for a minute then blows the fuse again.
Check the ground wire that is attached to the steering column/rack in the engine bay. That is the ground for the horn. If that wire is mangled, there might be too much resistance when the horn is pressed blowing out the fuse. That wire gets mangled a lot from people swapping out racks or dropping transmissions.
Brendan
I don't know about the 86, but on the 91 the horn fuse also handles cooling fan, so you could have issues in that circuit. If it only blows when you are actively using the horn, there could be a short inside your steering wheel/column.