Thanks for adopting this little hard-case and thank you for not giving up on him. You do not need to throw in the towel. We can fix this.
First - is there any possibility that this is a medical issue? I.E., could he possible have a chronic bladder infection, or stones? These types of conditions will make him feel as though he needs to urinate all the time. If you haven't ruled out a veterinary problem - it might be worth looking into.
I assume you don't punish him for urinating in the house...right? That never works.
Use a strong enzymatic cleaner on all areas where he has urinated. Even if it smells clean to you, he may still detect that that was an area where he has peed before and he will want to "recharge" the spot. Most pet supply stores and some veterinary clinics have excellent enzymatic urine eliminating products. Ask the store manager or your veterinarian for their recommendations on the best product.
Also, if your pet sleeps in your bed with you, this will need to stop right away. He'll need to sleep in a crate with a comfy bed at the foot of your bed. The reason for this is he needs to know that you (and everyone else in your family) are the pack leaders. A dog that understands he is not the alpha will not feel the need to mark.
BUT - while you are teaching him this lesson, I urge you to try this:
One of the absolute BEST products to use for dogs that mark are Belly Bands. You can either purchase disposable or washable varieties and they come in all sizes. They are like diapers and they wrap around your dog's abdomen, covering up his little fire hose! Dogs HATE to feel wet, so if he urinates, it will go into the material of the belly band and not your furniture or flooring.
You simply throw away the soiled belly bands, or wash them. They come in many colors and are very comfortable for dogs to wear. Your dog will learn very quickly that when he "marks," he is only getting himself wet and nothing else. It won't take long before he stops marking completely. You can experiment a little after three or four weeks of using the product by letting him go without for a while. Gradually increase the time he goes without and give him lots of toys and praise for behaving well. Also, be sure to let him be "naked" when he's on walks or in the yard. But in the house, put them right back on until you feel confident that the habit has been broken.
Good luck and let me know how it works out!
I am going to feature this on my radioshow at www.blogtalkradio.com/petplace
Thanks for writing in.
All the best,