Honda Civic hot/warm starting problem

This car starts perfectly if outside temps are 60 or below; very unpredictable after the engine has warmed up, and now even when the engine is “cold” if the outside temps are 70 or above. An earlier respondent helped me eliminate the main fuel relay as the culprit. Does this sound like a fuel or a fire problem? This is a 1990 Civic-DX, 1.5 liter engine.

Yes, it sounds like a fuel or a fire problem. Does it have fuel? Does it have fire?

I assume (perhaps wrongly) that there is no obvious fuel/fire problem because the car starts so well when cold and never misses. I have only tested carburetor engines for fuel delivery – is there a safe way to do that with fuel injection?