I adopted a 6-7 month old puppy about 4 days ago and was told that he was crate trained. In the house he has been great, hasn't had any accidents. On the other hand he very RARELY goes to the bathroom, which I weird. He will eat around 5 and not go number #2 for the rest of the night or in the morning. He doesn't sleep in his crate but he goes in the crate when I leave for work aroun 8am. I come home at lunch at around 12 pm and there is poo all over his crate, everyday. I am so confused and do not know what to do, its as if he is holding it until he goes into the crate. HELP!

Was he a rescue from a shelter or you got him from a friend?

If he was from a shelter he would have had a very stressful time and 4 days isn't much time to settle in.

How are his stools? Are they loose or appear to have any worms in them?

My suggestion if he is all clear in the health department is to take him for a nice long walk (about half an hour) in the morning or at night to try and encourage him to relieve himself.

My question is, how big is the dog, vs the size of the crate? If a puppy is put into a large crate, they will potty on one side and sleep on the other. A puppy like this should be in a small crate while learning to crate train.

The other half of this. I suspect the puppy is displaying separation anxiety. And when you leave, that is when he acts out and potties his crate. I would probably set the crate where he can see outside or in front of a Tv with it on or a radio playing at normal human talking volume to occupy his time.

To encourage him to go potty, take him for a walk. Don't allow him to be on his own schedule, put him on your schedule.