I'm not great at electrical so I need some advice. 69 Roadrunner, new engine harness 2 yrs ago, last year the dash harness melted and caught fire at the fuse box, had a lot of crappie splices, chafes but was running fine.

installed new dash harness this week, everything seemed to be working fine, had the car running a bit yesterday then hooked up my tach and accessory gauges to new fuse box today. again all seemed fine with the car not running, had key on for a bit and gauges lit up. cleaned up and started car for maybe 10 seconds and fusible link at the bulkhead went up in smoke. gotta get a new one, and I unhooked the gauges I hooked up today. So do i need to figure out if something is drawing to much in the car? or can a bad voltage regulator say put out to much juice and fry it?