Vapor Lock 2

[scott miller]

To recap:  it will crank, but won’t start or even fire when the engine is 
hot.  It starts immediately after cooling.  Hot idling is fine.  The problem 
has gotten gradually worse, with no repairs recently.  10v, 200k, 100k on 
injectors, 20k on fuel pump, a/c recently died.

I replaced the check valve on my fuel pump, no change.  That was my local 
experts theory, the pressure was bleeding off the line and allowing it to 
boil.  I loosened the fitting on the filter and got a good spray of fuel 
after it failed to start just now, so there is some pressure.

So far the responses from the list blame the injectors, but I’m doubtful.  
When my injectors went bad last time, it never got worse than a delayed 
start.  I mean just a couple extra compression strokes.  That was with 
several leaking injectors.  This time I can crank for several minutes, get 
it to fire on starter fluid, and still not get it to run.  Even after much 
cranking and firing on starter fluid it, won’t run until it cools for at 
least 30 minutes.  I’m definitely purging the engine of residual fuel from 
leaky injectors with all the cranking and running on ether.  It’s definitely 
lacking one of the elements of combustion when hot.

I’ll check the injectors next, but could it be electrical or a vacuum line?  
The after-run blower checks good.  The turbo hoses look good.  All the usual 
problem vacuum lines are fairly new.

My wife was excited about my getting a newer used quattro this fall/winter, 
now she’s getting skeptical.  This is not good!

Scott Miller
’90 200tqw
Holland, MI
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