You may want to start the troubleshooting from verifying proper connection of the upper spray arm manifold to the water feed tube at the back wall of the dishwasher (#6 & #1 on the diagram).

If there is nothing wrong, then most likely the cause of the problem is the pump chopper (#6 on the diagram). You can find more detailed instructions in one of our previous post - http://forum.appliancepartspros...hirlpool-dishwasher.html

Here are the breakdown diagrams for Kitchen Aid dishwasher Model KUDS30IVBT4

Good luck.