I had a cat, Tasha that did that also, she was a feral, that took me two weeks to catch only to be rewarded with pee every where. I ended up have to go to just plan dirt in her box to start out with. After watching her pee in my house plants instead of the litter box I decided to go with dirt. I guess being outside most of her life dirt was what she was use to peeing in so dirt is what worked. Slowly adding kitty litter as time when by.

But I would get him checked out for stones or infection as soon as you can. Do you notice him strain when he pees or an unusally oder to it? There just could be a problem that he's trying to tell you about.

Good luck.