well, i have a z6 swap in my 90 hatch, and if i drive it till warmed up then let it sit for anywhere from 5-15 minutes it will vapor lock and turn over, but not seem to get fuel to the engine. if the car has time to cool down, it doesnt seem to do it.

any clues? i'm thinking replace fuel filter and run injector cleaner

 

might wanna check your fuel pump too.. my friend had that problem with a toyota and that ended up being the culprit.

 

make sure your fuel pump relay is cutting power to the pump, some of the 88-91 civic/crx's had this problem(my 89 dx didn't but my 89 Si did), i would just get a new one from the dealer(30bucks) you can fix it if you know how to solder but i just got a new one. Heres a pic of where it is, it is on the drivers side floorboard right above the hood pop.

 

Main relay is a good suggestion, if you're not getting fuel to the engine.

If that doesn't take care of it or you are getting fuel, check out the TW sensor. Your symptoms fit the catagory of a 'hot soak restart' condition. Basically the TW sensor sends incorrect temperature information to the ECU, usually causing flooding.