if I/O engine fire may just need a new engine harness.... if up at the helm or short in the loom then may be best to take out and start again ...
dig around on the hull truth forum as you'll find color codes for most marine applications .....or just build up your own and label each end as what it's for ... other tip don't skimp out on gauge size and all ways better a bigger size up on longer runs ...and of course heat shrink butt connections and build a good earth run ....