Hello to another MN friend. Welcome to YT!!
Please don't spank Diesel, this will just set you farther back in training. Telling him no bite, and making a sound like it hurts you then ignoring him after for a while is a better approach. Positive reinforcement is key. Have you heard of clicker training? I highly recommend it. I used it on both of my Yorkies and had great great success with it, they know all the commands from come (most important, IMHO) to sit, lay, spin, rollover, shake, etc.
Here is a link to info for you, this is a great training tool!!!
http://www.clickertraining.com/