Faulty Injector - Clues

["Dave Zug" <dzug@delanet.com>]

I removed a plug with light brown coating all over, and a dark spot on one
third of the tip of the electrode ceramic.  It appeard this burn (or oil
deposit) spot is taking on material coming either from the direction of the
piston, or from the direction of the valve (angleplug alum heads), I cant
tell where it faces when screwed all the way in.

On previous inspection of this plug, a yellow coating was noted, and a part
of the ceramic tip was chipped off, like it had blistered. I went one plug
colder and now this burn spot, which is shiney and thin (wont flake off,
just turned the ceramic dark)

I looked at several diagnosis pictures, can't come up with one that matches.
The closest one makes the injector suspect.

The engine gets rather severe duty =(my foot), 383CI, 9.8:1, TPI, alum heads
and pistons.

The injector ohms fine, and fires with 12v.  GM manual says connect injector
test part # xxxxxx... Is this injector tester cheap and available??

TIA.

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