Won't start after it's warmed up on 2000 Chevrolet Metro

It seems like it always starts when it's cold in the morning. Then we'll drive it for 5-10 miles, then let it sit for 15-20 minutes or more, try to start it and it just cranks. Just turns over and nothing happens. At first it wouldn't happen every time, but now it is happening most times we drive it. It seems like then, we let it cool down for about 5 or 10 minutes and then finally it starts. The temperature outside here in Tucson is about 75 degrees. When it was cooler out it didn't seem to happen. Now maybe it has nothing to do with the temperature. Maybe it is just getting worse. Any advise, please.

Asked by for the 2000 Chevrolet Metro
I'm thinking fuel pressure concern. Fuel volatility and lack of consistent fuel pressure will cause a tough or impossible warm restart. Have the fuel pressure checked, as well as pressure bleed down.