Starts, however it fails every few months. It intermittently just cranks and doesn't turn over. I believe it to be a fuel pump relay or a main relay. Which one could it be?

They are the same.

Does the CEL consistently come on for 2 seconds and then go out, when the ignition switch is turned to ON (Position II)? If so, then the problem is likely with the distributor. Usually, replacing the Ignition Control Module (ICM) and coil solves the problem:

https://www.askmehelpdesk.com/cars-t...tml#post265896

If you can hear the fuel pump run for 2 seconds, when the ignition switch is turned to ON, the main relay and fuel pump are likely fine. 90%+ of most crank but won't start situations are electrical related, not fuel.

I usually recommend replacing the main relay, ICM, and coil, however, every 120,000 miles or 10 years, whichever comes first. These are the most problematic components on Hondas of this generation.