Ignition Fusible Link Blowing after Lean Burn Conversion

So take taillight harness and put it inline where the fusible link that's problematic or right off of the battery?
Tail lights are usually always hot.
Traditionally they get power from the 'always hot' portion of the fusebox.
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Your issue is in the J1 feed to the ignition switch. That's what you need to investigate, and where you might want to use a bulb to limit the power through (and light up when there is current flowing) or a breaker that will pop at 10 or 15 amps.