Sanyo has published the IR codes for this projector.  I can't easily turn the Google result into a link, but the projector uses NEC1 device 51.0.  Anyway, the main point is that the Power is a toggle, and the remote should send the same signal to turn it off or on.  Since that apparently doesn't work, we need a clearer explanation from you.

What remote are "currently" using?  The Sanyo remote that came with the projector?  A "Logoitech"? A Logitech?  Do any other functions work?  

If your current remote is a universal, did you learn the IR signals from the OEM remote, or are they from a library?