Grundfos kaput

I have a 4 year old Grundfos MQ3-45 that has locked up.
Before I spend 400+ on another one, I want to know if this is a common problem with these pumps.

The story: I went out of town and left the sprinkler running. The neighbor turned the water off, but when I came home the pump would not run. It is locked up and hums.

I have heard the same thing about that MQ pump from many people. It has a built in pressure tank about the size of a baseball. A small leak in the system can cause the pump to cycle on and off rapidly until the motor is toast. I would recommend a normal pump, which in the Grundfos is a JP5 or JP7, depending on the horsepower. This kind of pump with a standard pressure switch and 20 gallon size tank is much more forgiving.

If I were to design a new system, what would I need for dry run protection? My holding tank is shared, and has run dry in the past with my line being the first to go since it is the highest bulkhead in the tank. I would like to accomplish this at the lowest cost of course.

Great forum by the way. Lots of good replys and I love the search feature as well.

I think a simple float switch might be the best way. Running dry could also be the reason the pump is toast.

After calling aroung, I was able to troubleshoot the problem as a fried capacitor (it was once round and white, but now it looks like one of the weenies that was left on the BBQ overnight). The local motor repair shop had this huge 12.5 uF used cap that he sold me for a couple of bucks. The pump runs fine now, and we can all take showers again==Wahoo! Apparently this is a common problem with these pumps.

The pump doesn't have the top plate on because the cap wont fit under it, so I'm going to order 2 capacitors.

Thanks - Jack