drop in fuel line pressure on shutdown

[munrof at sympatico.ca]

Hi George:

How do you know the check valve is good? The test for the check valve is fuel line pressure retention - if it drops rapidly, the check valve is assumed to be bad. I had a brand new check valve installed in my old '86 5ktq that was bad right off the shelf.
The only other source of leak-down I can think of is leaking injectors, but I'd try another check valve first.

Fred Munro
'94 S4

>
> From: "George Kotjarapgolus" <gkot at adelphia.net>
> Date: 2001/11/14 Wed PM 12:37:20 EST
> To: "Quattro Digest" <quattro at audifans.com>
> Subject: drop in fuel line pressure on shutdown
>
> 1989 200 turbo engine: Car symtoms are that it will not start once engine is
> warm.  Can start it however by spraying starting ether, but only with
> protracted cranking.  Cold start has not been a problem.
>
> My mechanic concluded it was a vapor lock problem.  Fuel injector fan is
> working, it's sensor is also working.  Problem seems to be compounded by a
> rapid drop in fuel line pressure on shut down which supposedly hastens onset
> of vapor lock problem.  Fuel tank check valve is good.  Put on a used fuel
> distributor but pressure still drops rapidly on shut down.  What is between
> the fuel distributor and check value that would be causing rapid drop in
> fuel line pressure??
> Help
>
> George Kotjarapoglus
>
>