I've noticed this topic in a lot of forums and threads, but no one seems to have the exact problem I am having. My civic cranks and cranks, but won't start. Sometimes, after a few hours, I can get it to start - once it starts once, it will keep starting normally for the rest of the day, but will return to only cranking the next morning.
Took it to the shop and they replaced the battery, spark plugs and the distributor. Fuel pump does make pumping noise with the key in the 2nd position. Brought it home last night, seemed to be working fine - and then, the exact same problem this morning.

What else could it be?

I'd appreciate any advice. It's getting to the point that I'm wondering if I should just junk the car.

 

I would suspect the Main Relay.

 

When it won't start, check for sparks.

When it won't start, check if the check engine light cycles on and back off when you turn the key on but don't try to start. Use a jumper or OBDII scanner to see if there are any ECU codes.

 

Thanks!

@mk378 - The check engine light does cycle on and back off. I don't have a scanner to check for codes, unfortunately.

@droopy128 - I will look into checking the main relay.

Maybe I'm placing too much faith in my mechanic, but I'm pretty sure he checked the main relay and for any codes. It seems like this problem might be something weirder...