[T3] Need help with erratic no start/start condition-Resolved

[Norman Roush]

On Tue, Sep 27, 2011 I
 wrote:
 My daily driver '68 Squareback with MT and FI has recently developed an
erratic no start condition. Car will start and run fine for days/weeks. 
Ran errand this AM.  Car started fine drove for about 20 mins. Stopped for
15-20 mins and restarted fine and went home. After 20-30 mins tried to
start car but turned key, heard relays but fuel pump did not prime. Checked
relay, fuses and elect connections at pump.  All appeared OK but pump would
not run. Waited 30 mins while working on options, tried again, pumped
primed OK and I drove to work.  I do not think I really "fixed" anything . This sequence has happened 3 times in last 5-6 weeks.  I live in Sunnyvale,
CA so heat/humidity is not a problem.  This has happened at 9:00 PM when it
was cool.  Any suggestions?

and Mark Fuhiman replied:

Next time it starts, runs and drives fine find a place to pull off the
road and start playing with the wiring harness in the engine
compartment.  With the engine running wiggle the wires around the
large ECU "plug."  Wiggle all pieces of the harness, including the
wire that goes through the bulkhead for the pump.  You might find a
bad wire or connection that causes the engine to stop/start.  That's
how I once found a bad wire in my harness that caused symptoms similar
to yours.

Mark
'69 Fastback

I took this good advise and found the problem to be the connection of wires #24 and #16 where they come out of the ECU and plug into the dual black (in my case) connector. I installed a new FI harness built by one of the guys on The Samba lists and the female spade plugs are a bit big for this connector and needed to be pushed in more forcefully.  Anyway car has been starting everytime since then.  Thanks for all the other suggestions, I'm keeping them for future reference.
 
Norman
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