Okay, that model number did not come up but I used it and I think your model number is
FDB520RHB2A. Does it drain good when it goes in to the bucket? Also, does your dishwasher drain line go in to an air gap?
It is pumped out. It should not free flow at all. Okay, so if the water goes in to the bucket with slight force when you turn the dishwasher on that is telling me that your drain pump is working and you need to check your piping. I am sending you a link to explain the air gap.