I agree with Anafiel above and, as you're finding out, this stuff can be tricky (especially when computers are controlling the ignition).

Best thing that I know of is the EVTM - Electrical & Vacuum Troubleshooting Manual.

I don't have one myself but some people here have had high praise for the things.

There are a few pieces of 'em on fordfuelinjection.com:
Ford Fuel Injection » Truck EVTM’s

For you and a 1986, here's one you can purchase:

1986 FORD BRONCO F150 250 TRUCK ELECTRICAL SHOP MANUAL | eBay

You might also check out this thread from a few years ago, see if it helps you (it's from the sticky above):

https://www.ford-trucks.com/forums/8...need-help.html