Start light flashes on whirlpool ADP 4504?

When my dishwasher is filling the start light seems to come on and off and the dishwasher fills slowly. When the light comes on i can hear the pump but then it goes off for a second and then comes back on. This happens until the dishwasher is full enough to start the cycle. To me it sounds like a blockage on the inlet but is there a filter in the inlet side? or could it be something else causing it? Thanks for any help in advance.