OK- I feel like an idiot since I did not put correct info in my first post, so I have to re-post this...Sorry, I'm still trying to learn correct terminology. Anyway, ENGINE DOES CRANK BUT IT DOES NOT START....
btw - thank you, Mechanic & TomD on your responses! Could you please update/edit them, now that I post correct version of my problem:

1987 volvo 240DL, 140K

I have a hot re-start problem with this car. Every morning it starts just fine. If I make a short trip to a store, turn engine off, and try to re-start, it won't start. ENGINE CRANKS BUT DOES NOT START...So I just sit there for 10-15 minutes for things to cool off and then it starts just fine....I only have this problem in summer, at high (more than 80-90 F) ambient temperatures. Sometimes it even shuts off in the middle of driving...again, it starts fine and drive, ONLY after I wait 10-15 minutes. During winter, it drives and starts perfectly, every time...

Fuel pump relay was installed new, two years ago. Battery is fully charged/new. Spark plugs are 6 months old/new. Cap/rotor/spark plug wires where installed new 2 years ago (at 120K)

any ideas what may be wrong? Could it be that ignition coil/wire went bad?
Or something with the starter?
...thank you in advance for any advice.
d