drop in fuel line pressure on shutdown

[George Kotjarapgolus]

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