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

[Grant]

Thanks Kneale,

Well, if what you say is true, then its operating correctly (e.g.: not 
turning on until the engine turns).  However, I'd swear I hear the pump 
before my S6 (2002) turns ... I'll check it at the fuse, easy enough.

There's certainly a cold-start function, but I think its just a 
richening until the car warms up, i dont know of a sperate valve.

Thanks,

Grant
On Nov 13, 2005, at 3:57 PM, Kneale Brownson wrote:

> Not familiar with the newer cars (funny to call a 10-year-old model 
> newer),
> but the circumstance you describe sounds like a cold-start valve 
> failure if
> there is a cold-start valve or function on the V6s.
>
> BTW, I think Audis since about 1990 require engine turning to trigger 
> the
> fuel pump operation.  Pretty sure that's the case on our V8s and 
> 200q20v.
>
>
> At 03:18 PM 11/13/2005 -0500, Grant wrote:
>> 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
>>
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