I have a whirlpool dishwasher (gu2500xtpq6) wont fill up

You most likely opened the door before it finished.
Press and hold start to reset

If it fills with water properly then stops, and especially if there is a humming noise, it is possible that

- motor start capacitor has failed
- drive belt has slipped or snapped
- belt tensioner spring has broken

Sounds like it maybe the pump

dish washers have a fill valve. the water supply line most likly has a net like filter that is stoped up with trash. Or fill valve is bad.
same thing happens to washing mashines. when they start filling up very slow you will TURN OFF water supply and diconect hose, look inside and there is the problem.

I doubt the H2O tank temp would have any affect... to fix the problem you will need to pull the unit out and replace the supply line from the valve to the elbow... I would recommend braided line.

If your talking about the fill tube that loops up the side of the unit it usually is just seperated at one of the fittings and can be pushed back intp lace or recalmped... otherwise you will have to purchase a new oem tube.

could be but if it is filling up when it is not running then you have a bad solinoid

I fit won't fill then apparently you're not getting any water to it, which means it not's fixed. Did you turn the service valve back on since the repairs were made? Sometime when you turn a service valve off they fail to re-open. Crack the inlet water line and verify that you have incoming water.

reach inside your d/w and jiggle the mushroom shaped float switch located on floor of d/w. should move freely up and down if its stuck up(or something lodged under it your unit wont fill with water

The pump may be clogged or the motor start capacitor may be bad or the fill switch may be stuck or the timer may be bad. Fill the dishwasher by hand to just below the door level and close it then see if it will run. If it then runs correctly the problem may be the fill switch. If not, it could be the motor, the cap, or the timer

  Check your connection where you connected dishwasher to power cord.