At 03:44 AM 7/28/2012, neil n wrote:
>At this point I'm pretty sure that with time, heat from the engine
>heated up the surrounding metal enough that it caused the casing to
>burn.

See if those dark marks don't match the contour of the black rubber
grommets.  I'm still going for plasticisers in the harness cover
leaching plasticiser/whatever out of the grommets.  As an experiment,
set a clothes iron on low and see what happens if you overheat a bit
of that cover.  I'm betting you'll see it melt and flow rather than blacken.

>  I guess it can't hurt to double check the FI wires as they show
>a little heat damage too.

Neil, if the wires had gotten hot you'd see melting, not
browning.  They're ordinary vinyl-covered wires and they'll melt and
stick together long before they get brown.

>  All the wires from the idle stabilization
>unit show continuity but that's just a test with a small load from
>DVOM. Still. They don't show signs of heat damage.
>
>The wires to the B+ post inside the junction box looked OK but a fuse
>sounds like a good idea.

They're fine, plenty big, no problem at all - until you get a
short.  At that point you've just connected the battery to ground
through whatever little wire in the harness got shorted to
ground.  Since everything as far as that B+ post is honking big,
guess which part smokes and melts the whole harness together...

Yrs,
d