Hot start problem 88 5kt automatic

[Eric_R_Kissell at whirlpool.com]

My first guess was the vapor lock issue.  Is the injector cooling fan
functional and the shroud able to direct cooling air over the injectors?

Can he pop the hood sometime when he parks and see if it will restart after
less than 20 minutes?  It was what, about 37deg F this morning here in
Northern Ohio, so I would think things would cool relatively quickly.

If you suspect something in the fuel pump relay, can you swap one from the
other working car for evaluation?  I cannot recall which systems go through
the fuel pump relay. I seem to recall the ox sensor heater may.  I would
need to consult the wiring diagram to see.

Also, might this problem be related to either leaky injectors or a leaky
fuel pump check valve? I suppose if this was the issue the car might
eventually start without the required cool down.

My 1991 200q 20vt has a similar issue in that is slow to start after being
stopped about an hour.  Cold it starts fine (though a little long in
cranking) and hot it seems OK, but when it is just warm after sitting about
an hour it cranks long enough that bystanders begin asking if I need a ride
somewhere.  Luckily the primary role of this car is driving to work rather
than running errands, so the problem is not a daily nuisance. I believe
this may be related to a sensor and cold versus warm versus hot start
enrichment, though I need to research it.  Does the 1988 5000t have a
similar sensor input to the ecu?  Is this a role of the multi-function
sensor?  I have two cars with MC-1 turbo engines, so you would think I
would know the answer to that.

You are right in considering heat-related failures in systems that would be
required for starting but not once the engine is operational. There could
be an electrical connection that is opening up when hot that regains
continuity when it cools. What about the flywheel crank reference sender?
Is that needed for startup but not once the engine is running or is it
required while running?

Is there a vacuum leak that opens when hot but not so much that it kills a
running engine but maybe enough that a good mixture for starting cannot be
obtained?

HTH,
Eric Kissell
Tiffin, OH