Ignition troubleshooting on a Mk.1 (v. long)

[zeroid at hotmail.com (Ben Channard)]

Abstract:  Have fuel but no spark.  Battery and starter are good.

My CIS 1981 Mk.1 wouldn't start one evening.  To my surprise, It started and 
restarted the next morning but when I finally wanted to drive away an hour 
later, it wouldn't start.  Fuel pump buzzes and jumpering the fuel pump 
relay doesn't remedy, and I can smell fuel so I've focused on ignition.

I followed the Bentley (R/S/J '80-'84) ignition troubleshooting protocol but 
have several ambiguous results and am still left with a non-starting car.

To test the coil for spark the Bentley calls for a 1000 ohm suppression 
resistance at "each end of the cable" but I'm not sure how to set this up.  
I tried the test without a resistor and saw nothing.  Also saw no spark at a 
grounded spark plug.

Tested the coil's resistance between the center electrode (#4) and terminal 
1and got a reading of 4.2K ohms which is within range but the reading 
between terminals 1 & 15 was 0.9 to 1.0 ohm which is outside the acceptable 
range of 0.52 to 0.76 ohms.  Thinking this was the culprit, I bought a new 
coil (Niehoff brand) and ignition was still dead.  The new coil also had a 
resistance of 1.0 ohms between terminals 1 & 15!  Is this coil bad?

Voltage at terminals 2 & 4 of the ignition module harness is 12.1V which is 
OK.  (As an aside, the photos for Fig 4-4 and 4-5 are switched in my seventh 
revised edition of my Bentley).

Tested the ignition module by detaching the distributor harness and 
measuring voltage at terminals 1 & 15 of the coil.  Turning on the ignition 
gave a constant 0.56V instead of the 2 volt or above which should fall to 
zero after a couple seconds.

Ignition module seems bad so I tried two other boneyard modules and they 
don't work and in fact give no voltage with the above test.

Tested the Hall sender by measuring voltage at terminals 3 & 6 of the 
ignition module while hand turning the crank--voltage alternated between 
3.03V and zero which is normal.  BTW, the car died while driving about a 
week and half ago due to a broken Hall sender wire.  Replaced the sender 
with a used one and car started up fine.  The pin which anchors the trigger 
wheel to the shaft fell out when trying to lever out the wheel.  Can this 
pin cause problems since it fell into the distributor body?

Other miscellaneous checks--all three wires from the distributor harness had 
continuity to the ignition module.

Can the oxygen sensor box cause a no start?  How about the ignition switch 
even though the fuel pump and starter and all electricals are activated by 
the key?  Can I rule out the distributor?

Can the new coil be bad?  Is it likely that all three ignition modules are 
bad (albeit they are all used)?   I'm leaning toward the ignition module but 
I'd like to eliminate any likely suspects before springing for a new module. 
  Thanks for slogging through this email.  Regards, benton-----

_________________________________________________________________
Express yourself with MSN Messenger 6.0 -- download now! 
http://www.msnmessenger-download.com/tracking/reach_general