Are you talking about the fuse that is near your battery?
The reason I ask is because that fuse is there to protect the wire from the fuse to the amps from melting from too much current. More than likely what's happening is that your amps are drawing more than 80 amps and thus overloading that fuse.
So let us know what gauge wire you have and what kind of current draw your amp(s) produce and we can go from there.
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Ill say i go by His and Al's thoery of "Your getting sprayed" Doesnt matter what it is. Grandma in the 1982 LTD is gettin the bottle.