FW: Ignition Switch Failure Mode

Geraint Lloyd geraintlloyd_qc at yahoo.ca
Fri Jun 19 08:01:19 PDT 2009

Actually it sometimes starts fine after it has been sitting for a while.
I was assuming that a check valve failure would be mechanical, so unlikely
to be intermittent.
But I appreciate that i could be wrong
And the b at 5tard check valve is only 2 years old anyhow.....

-----Original Message-----
From: 200q20v-bounces at audifans.com [mailto:200q20v-bounces at audifans.com] On
Behalf Of Kent McLean
Sent: 19 June 2009 10:51
To: quattro at audifans.com; 200q20v at audifans.com
Subject: Re: FW: Ignition Switch Failure Mode

kneale at knitknacks.com wrote:
> Do you know that you have no spark or fuel while cranking?  If so, I'd
> suspect the ignition and engine speed sensors.  They have to be providing
> the ECU a signal in order for it to activate the fuel pump relay and
> sparking system.  Those things are twenty years old now.  They fail
> commonly much sooner on V8s because they're located near the driver side
> exhaust plumbing on V8s.  On 10valve cars they escape that heat issue, but
> they're still subject to age.

Given that it's hard to start only after it has been sitting for a while,
I suspect the check valve at the fuel pump. Does the car start after 5-10
seconds of cranking?  Then it's the check valve.

I don't believe the ignition switch would not work after it's been sitting,
but then magically work if it hasn't been sitting. Usually it will fail
to spring back, leaving your key in "start" mode; you can turn it back a
bit to set it to "run". Either that, or it fails all together.

Kent McLean
1999 A4 Avant, V6 Tiptronic
1991 200 TQA #3, with mods
1990 V8 w/5-speed and other mods
gone: '91 200 TQA x2, '94 100 S Avant, '89 200 TQ "Bad Puppy"

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