Grunfos pump that even when all outlet valves are off the pump keeps kicking in an out?

Right after the discharge outlet, a non-return valve or check valve is usually installed. Check this one out, maybe it is worn out. You may have to replace it. Do this and get back to me if it does not work out.

Can you describe the pump you have? Is it used for household water or a sprinkler system? Typically a household pump will have a storage tank and a pressure switch. 90% of the problems with a pump not turning off is due to the pressure switch.

I am just guessing but it appears there is a restriction such as a partally closed valve.

If you have a gate valve on the discharge of your pump, and if its shut, and the pump "kicks on and off" cycling. then its the foot valve or non return valve leaking.

Plug grunfos into any timer with 3-prong outlet.
Analog: Intermatic TN311C up to 3-on-off per day minimum 1/2 hour
http://waterheatertimer.org/Intermatic-timers-and-manuals.html#TN

Digital: Woods 50009 or 59377: 7-day programming down to minute
http://waterheatertimer.org/Woods-timers-and-manuals.html#50009

Generally a Grunfos without timer will operate each time water temperature inside pipe falls below 90 degrees.
http://waterheatertimer.org/Water-heater-recirculation-system.html
So when timer turns ON, then grunfos receives power and thermostat must sense temps below 90 before pump turns on.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Water pressure is what makes the unit kick on and off. If its kicking on by itself most likely water is somehow draining back into the pump. Start by checking the flapper in the flush valve inside the toilet tank, it may be leaking water into the bowl and from the bowl into the pump. Also inspect the check valve inside the 90 degree elbow where the waste is pump out from. The check valve may not be closing properly and is allowing waste water to drain back into the pump creating water pressure making the unit kick on and off by itself.

First check with a pressure gauge to see that the pressure is, indeed, dropping. Then, if it is possible, turn off the outlet valve to isolate the pump.
If pressure is still dropping, there is probably a check valve on the inlet of the pump that prevents water from the high pressure side from leaking back to the inlet piping side.
To test this, let the pump run and pressurize the house and immediately close the valve for the incoming water. If the pressure holds, then open the inlet valve and see if the pressure drops. If it drops, the inlet check valve has to be replaced (or cleaned).
Gary

Water pressure makes the unit kick on and off. It will turn on by itself if water is somehow draining back into the pump. It could be water leaking from the toilet tank into the bowl and from the bowl to the pump or the flapper on the check valve inside the discharge elbow may be stuck open or could be defective and allowing waste water to drain back into the pump, once it builds up enough water pressure inside the pump, the unit will kick on and off by itself.

Either the breaker is bad or you have an electrical problem. Unless you know how to work with electrical problems call for service. If you unplug the hot tub and plug a lamp or hair dryer into the outlet does the breaker trip? If yes, call an electrician. If the outlet is fine call for service on the hot tub.

If you have valves at the pre tank you can run it till it shuts down then close the inlet valve and the outlet valve. Wait and see if it goes on again. If so you have a problem in the pressure tank or the switch mech. If not open the outlet valve and wait. If it starts you have a leak somewhere in the house. If not open the intake valve and see what happens. If it kicks on then you have a problem with you check od backflow valve. If this is a shallow well pump it could be in the supply line also. Good luck.