water drains while arm sprays in washing mode

Dishwasher Repair
,
1

during the wash and rinse cycles water drains at about half normal draining velocity. this causes too little water to complet the wash and rinse cycles. at the end of the wash and rinse cycles, normal draining volume is observed. what is causing the water to drain out during the wash and rinse cycles. this happens about half of the time, not always but the washing action is impaired and is no longer reliable. whirlpool MODEL# DU800CWDB5

3

Here are your parts
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=262283&diagram_id=103804#d103804

Here is the wiring diagram
http://www.servicematters.com/docs/wiring/Wiring%20Sheet%20-%203379194.pdf

Here is a manual. Not great but the best I could find. It covers a number of different units and is confusing.
http://www.servicematters.com/maytag_library/docs/16008775.pdf

I would start by checking Item 3 in Section 5