So twice now, I've encountered this problem in similar conditions, and feel the need to ask.
What: vehicle turns over, but will not catch.
When: after having sat for ~8 hours with windows rolled up, on warm day - between 60º-70ºF.
This is the second time that it's happened to me within 7 days, and the weather is only getting warmer presently.
The first time, it would crank, but not catch. I waited about 10 minutes after having rolled down the windows, tried again, and it started.
Today, it turned over and caught as it usually would, then within 5 seconds, stalled. I tried to start it again, and it just cranked away. I rolled down the windows and opened the sunroof. I tried to start it again about ever 10-15 minutes to no avail. Finally, after nearly an hour, it started.
I read the post at https://www.hondacivicforum.com/foru...hooting-82927/
and it seems like it may be the Main Relay. I've only just checked the cables running to the (forward) front end of the car, and they looked immaculate. I will have a closer look at the engine compartment fuse array and under dash array tomorrow.
Each time I turned the key to acc II after the initial start, I could not hear the fuel pump energize - that is, until the car finally started. Just to possibly eliminate a faulty fuel pump from the equation, how would I go about testing it?
Any ideas about the situation?

 

DIY section on Main Relay, just re-solder mine..