My dishwasher won’t drain completely. I started at the disposal, checked for obstructions…found none. While the drain hose was detached I ran the drain pump and the water flowed out just fine. The pump doesn’t pull ALL of the water out. Does my dishwasher think that it’s empty when it’s not? Thanks in advance.
No,
Your dishwasher cannot determine if your tub is completely empty.
Once the drain cycle has ended, there may be as much as 1/4 inch of water left in the center of the pump,below the spray arm,and a small amount of water may remain around the black gasket that seals the pump assembly to the tub, this is normal.
Is there more water than that ?
If so, there may be a problem with the drain pump,or the drain flapper.
Please varify the water level that remains after the drain cycle and let us know.
Thanks 
Here are your parts
Replacement parts for MAYTAG MDBF750AWQ Dishwasher - Undercounter | AppliancePartsPros.com
Here is the tech sheet
http://www.servicematters.com/maytag_library/docs/16023221.pdf
And a manual
http://www.servicematters.com/maytag_library/docs/16021814.pdf
[COLOR=“Blue”]The pump doesn’t pull ALL of the water out. [/COLOR]
If the pump is not pushing all the water out could be a dirty filter, stuff clogging the water flow or the drain pump itself.
Also check the flapper valve at the drain pump.
[COLOR=“Blue”]Does my dishwasher think that it’s empty when it’s not?[/COLOR]
The unit has no way of knowing when it is empty. This is just a timed event.
If the unit pumps it all out,the pump stops and then water flows back in it could be the air gap if you have one installed, the drain hose is not looped high enough above where it enters the disposal or the pump check valve re: it is sihoning water back out of the disposal.
[quote=Joe / APP Team;253380]…
Is there more water than that ?
If so, there may be a problem with the drain pump,or the drain flapper.
Please varify the water level that remains after the drain cycle and let us know.
Thanks :)[/quote]
YES, there is more water than that. The water level comes all the way to the bottom edge. It used to leave just a tiny puddle.
Are you sure the drain hose is not clogged ?
Check the drain inlet at the garbage disposal and the disposal for clogs.
and the mesh filter, under the horse shoe shaped pump cover for debris and clogs.
You may have to remove the accumulator and check that as well, if you have to go that far, then remove the drain flapper assembly(red plastic ring at 2:00 o’clock position) and check for warped, missing, damaged,flapper(s)they should be flexible and straight.