Hey guys, anyone got a good starting point for an 84 22r that keeps blowing the 7.5 ign fuse? I runs for awhile, then blows the fuse and the truck will die if you let it idle. We're about to start testing all the stuff on that circuit, but any help would be great. Thanks.

 

Get a LARGE supply of fuses, disconnect everything you can in that circuit, see if it blows, add 1 and only 1 item, see if it blows, keep going until you've got the bad item. It'll be the first to blow the fuse.
Unless you've got some random homotron running around the cricuit...You know, a "homotron": An electron that likes to run around blowing fuses...
That's an electronics joke, btw

Edit: I found this wiring diagram, , figure #58 shows that the "ign" fuse only powers the Main Power Relay coil when the ignition switch is in run. Try that first...

 

Haha, funny. Thanks for the help. That points us in the right direction. It's wierd because it will run fine for a random amount of time (sometimes a week of driving, sometimes less), and then blow again. Thanks again for the diagram.

 

Has he added anything or rewired anything? (Stereo, fog lights etc)
Most likely culprits.
If so, I would put an amp meter inline with the fuse - maybe it's drawing right at 7.5 amps - no short, just too much load. Then add an additional ignition relay for the extras.