RE: Hot start problems- 5kcstq

["Livolsi, Stephane" <livols1@investorsgroup.com>]

I used to think that too, but I rigged up a test to check.  I spliced in
a 12 volt direct supply to my fuel pump via a dash switch (some of you
are probably starting to wonder just how many extra switches does this
guy have in his dash...but I digress) So before starting the car, I
would run the fuel pump for a minute or two.  NO EFFECT AT ALL.  It was
just as hard to start.  I once tried leaving the pump on for several
minutes to build up pressure and same thing- no effect, still did not
want to start and my battery did not appreciate it either.  I am almost
convinced that this hot start problem is related to the air flow plate
and/or the warm up regulator and that is where I am focusing my
troubleshooting as well as still looking for any vacuum leaks.  When the
engine is cold, the cold start valve primes the engine, which fires and
creates enough vacuum to lift the air flow plate and open the injector
plungers.  When the engine is hot, there is no priming from the cold
start valve and if there is a big enough vacuum leak the airflow plate
won't rise to open the fuel injector plungers.  I imagine it could be
one large vac leak or many small ones (valve cover, cracked lines,
injector seals, etc...)This is my theory anyway, but I am willing to be
proven wrong.  

Stephane Livolsi
180 Yorston St
Williams Lake, BC, V2G 3Z1
ph 250-392-2637
fax 250-392-2693

'86 5KTQ stock (if you don't know what it means, you aren't in the club)

>----------
>From: 	Robert Dalton[SMTP:rpdalton@onebox.com]
>Sent: 	December 31, 1999 9:21 AM
>To: 	TM
>Cc: 	Quattro List
>Subject: 	Re: Hot start problems- 5kcstq
>
>I think it could be a weak fuel pump.  On my 1990
>Audi 100, sometimes the fuel pump fails to start
>right away.  You can hear the problem if you listen
>carefully, because the fuel pump is supposed to
>run for 3 seconds when the ignition is switched
>on (before starting).  This builds fuel pressure
>and makes for easy starting.  My fuel pump sometimes
>just sits there, failing to start during this 3
>second prep time.  The result is either an immediated
>start and quick die out, or lots of cranking before
>starting or both.  Interestingly the problem is
>more likely to happen when hot, because then the
>fuel pump wires are hot, draw less power from the
>battery, and can't get the pump moving.
>
>Now if I can only find a place to get this pump
>for less than the atrociously high prices they
>want in Northern Virginia. 
>
>-- 
>Robert Dalton
>rpdalton@onebox.com - email
>(703) 234-3969 x1020 - voicemail/fax
>
>
>
>---- "TM" <mizutanit@mindspring.com> wrote:
>> Hi listers,
>> My car runs flawlessly on cold starts, but recently,
>> I've had some
>> serious problems with hot starts. The starter
>> fires and the engine
>> cranks up, but it seems like it can't maintain
>> any idle and the
>> engine dies after a few seconds, trying to drop
>> the idle to 500 rpm,
>> which isn't going to happen. Funny thing is,
>> if I can get it fired
>> up and moving, the problem goes away. Last night
>> I had a bit of a
>> scare because it took 5 tries to get the car
>> going. Then, later on,
>> after it was parked for a while (couple hours),
>> it started and ran
>> fine.
>> 
>> My guess? Multi-function temp switch, or some
>> other similar device.
>> Can someone please help in diagnosing this problem?
>> Greatly appreciated,
>> as I will be undertaking replacement of my dash
>> lights and A/C programmer
>> today and don't need any other problems.
>> 
>> Taka Mizutani
>> '86 5kcstq
>> 
>
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