Could be that your fuel pump is bad/going bad. You might want to replace it with a GSR pump or a Walbro.

:edit: It could also be that your fuel filter is clogged. Oh, are you using the fuel line that runs from your filter to your fuel rail that was originally on your civic or are you using the GSR line?

I STRONGLY suggest that you upgrade to the GSR line. I had a lot of problems using my stock civic line because it doesn't allow as much fuel through. You can get one of these at a reasonable price from www.sohfast.com