More on 1995 A6Q ignition switches and (lack of) fuel delivery

[Grant]

As some of you may recall, I've been chasing a gremlin that has 
resulted in 4 supposed ignition switch failures in a "b5" 1995 A6q 
automatic (12V v6).  The first failure was the typical - the switch 
would not return automatically to the "accessory" position, resulting 
in a loss of interior power bits, until you manually turned the key 
back.

Replacement, now 18 months or so ago, resolved this problem, and it has 
not recurred.  What has happened, is  that the car fails to start. It 
cranks and cranks, but wont start.  This begins as intermittent and 
becomes more consistent.  Voltmeter testing confirms that when it 
starts, 13V is present at the fuel pump fuse, and when its not, 0V is 
present.  If it cuts out mid-start, the voltage drops to zero.  So its 
not the pump.  Note that the pump is not energized in the accessory 
position, whcih surprises me. In all my other audi's (past and present) 
it was - e.g.: turn the switch to accessory and the pump runs audibly.  
Also note that a few times it started and idled ok, but quit when 
shifted into reverse.

The switch has been replaced twice to fix this. Both times the 
replacement worked for anywhere from 2-6 months, then recurred.

This time I took it apart myself (thanks to Bob Myers for instructions. 
BTW, even more extensive instructions are available on AudiWorld, or as 
PDF from me now).  It seemed that if I disturbed the harness, it could 
fix the problem. So I disassembled everything, inspected the harness 
(found nothing obviously broken), cleaned all the contacts (cramolin), 
and put it back together.

Now it starts consistently, but will stall out if it has not run 
recently. Oddly, given my note above, if you leave the switch in 
accessory for a few seconds and then start it, it runs fine and will 
not quit/stall.

So - does anyone have words of wisdom?
- might a fuel filter be clogged?
- should the pump energize in accessory?
- any other advice?

Grant