My 99 Civic will crank over and sounds like it might start, but it doesn't. There is spark at all 4 cylinders and there is fuel at each cylinder(plugs are wet after repeated cranking). The spark is yellow rather than white at each plug. I don't know if this makes any difference since I'm thinking that any spark will ignite the gas in the cylinder. Any suggestions as to what might be causing the no-start would be appreciated.

Replace the Ignition Control Module (ICM) and coil:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

Thanks for your quick response. I will try replacing those parts on the weekend and let you know the results. Thanks again.