Grundfos runs intermittently and needs power cycle to get going again

New pump? Or old? Previously used pumps sometimes get stuck. They do not have a lot of starting power and very little debris or rust can keep it from running. Remove the 4 Allen head bolts from the motor to volute. Spin impeller by hand. Should have no resistance. If that's good reinstall and try again. If you have verified power to the pump and it is still not working get a new pump.

Found on a '92 Toyota pickup w/V6, a bad/intermittent fuel pump relay.
Had fuel rail pressure so fooled us initially, found by listening to pump run then quit, cycle key and pump would run again then quit, sometimes when trying to start, motor would start and run for a few seconds then quit, or not start at all, this created by intermittent relay operation. Need two people, one at passenger side by tank and other to work ignition switch.
Relay located behind right, passenger kick panel, dealer item I believe about $28.00.
Just another possibility.

Normally I disconnect the power and try to spin the shaft, I do not know this pump well enough to tell you how to get to the shaft. I would listen closely to the motor then turn it on, if it hums it probably has a bad start capacitor. These tend to fail quickly when the pump cycles a lot.

When I start a new cycle, I first hear the pump run to empty out all remaining water, and after that I hear the motor run for the regular washing cycle, but there is no water in the dishwasher. After a few minutes, the cycle stops, and the washer claims the dishes are 'clean'. When I try starting a new cycle over and over again, about one in 20 times, the cycle will run normally with water. But then the next time, the problem starts all over again. Once a cycle starts correctly, everything works fine, including the rinsing.

Hi Hayley.

Please allow me to try to help you.

Random water pumping or intermittent water pumping, appears to be quite a commonality with the Grundfos pump. The solution to this is quite a bit of process, the details of which you can get here...
http://inspectapedia.com/water/Intermittent-Water-Pump-Cycling.php

I have also attached a video, trust that gives you a bit more insight.

Hope that helps.

Best wishes. Regards.

I have circulation system on my water heater.
First system gave out.
When taken apart, it was clogged with sediment and couldn't be cleaned.
Put sediment filter on line, and second circulation system works fine, and timer works fine too.
I haven't had timer problem, but have investigated timer motors running fast and slow.
My friend who re-winds big pump motors says homeowner timer motors are engineered for 60Hz.
As long as electric power is 60Hz (60 cycle AC), then motor will keep exact time.
Since your household current is 60Hz and other electro-mechanical timers run correctly, then it's likely timer motor has a flaw or has gone bad.
Grundfos water heater re-circulation pump and timer are sealed unit.
Grundfos manuals do not show parts list or repair steps:
http://waterheatertimer.org/Water-heater-recirculation-system.html#Grundfos
It's aggravating when expensive household timers like Malibu power packs and Grundfos pumps are not made to be repaired.

I had the same problem. The washer control board has an intermittent failure. If you unplug power for about 30 minutes then plug it back in you will get a PF code (power failure). Ignore this code and push start again. It may run till it finishes the cycle or it may start cycling again right away. A new board costs about $180 at repairclinic.com

This is a problem with your bladder in the pressure tank or the pressure switch. Ether one will produce this cycling on and off. Good luck.

I have the same problem and have found that the inlet check valve has a broken shaft in the center of device. It is a multi-piece plastic unit and it looks as if it is not quite seating and therefore the internal pressure leaks slowly back into my low pressure suction line. The pump will start and the pressure will build then shut off for about 30 minutes then cycle again. I am going to replace the check valve.

  Check your connection where you connected dishwasher to power cord.