[urq] No hot start (speed or reference sensor?)

[n-engelbert at terrans.net]

Recently on my 83 UrQ DA900453, the car has started fine when cold, but
will not restart when hot.  When cold, the tach bounces as I'm cranking,
presumably at the speed the engine is cranking, but when hot, the tach
does not bounce, I don't believe I have spark, and consequently, the
engine won't start.  As of last fall, the fusebox (under dash) and
ignition switch were new.  Spring 2003 the transistorized ignition switch
in the glovebox was new.  Once I can get the engine to start, though, it
runs as if nothing is wrong, leading to the belief that I may have a flaky
sensor.

The question is:

Is there a sensor that the ECU only uses when cranking to determine TDC,
and therefore, when to spark?  This sensor would drop out of operation
once the engine is started.  I'm going to stop by radio shaft to pick up
some freeze spray to bring the offending sensor back to cold on hot
restart until I swap in my 3b sometime after the CT UPG.  I skimmed the
IST documents and didn't see anything on my first time through.

Does anyone else's car's tach bounce when cranking?  Should it move when
cranking?  My 90 and 200q20v's tachs don't bounce that I remember.

The car's been in storage for a while, but this happened last fall as well
before I parked it for the winter.  I can check ECU voltage and step
through the IST instructions if I can't find the problem quickly without
removing the ECU (easy, I know).

Man, I need a scope,

Nathan Engelbert
83 UrQ DA900453
89 90q
91 200q20v donor
91 200q20v avant