Sump runs every two minutes

[Dons]

I've got a little different sump pump situation. The sump has been running fine, but a couple days ago it began kicking on every two minutes or so. It only runs one or two seconds, then shuts off. I can trigger it manually and it runs fine. I did drill an eight-inch hole to prevent air lock prior to all this. Anyone know what the problem might be? It's obviously not draining the sump each time it runs. There is a backflow preventer on the line. The sump pump has to pump water up about six feet.

don s

[joed]

Possibly the check valve is failing intermittently and letting the water flow back into the pit.

[CR500]

Hopefully you drilled the hole BELOW the check valve! It should be between the check valve and sump pump.

[AllanJ]

The start switch may be malfunctioning. You said it works fine when you trigger it manually, giving the float a good push so the switch clicks on firmly and the other part of the mechanism (for stopping) doesn't (shouldn't) kick in until the water level lowers significantly.

Whereas for the time being the water level rising by itself lets the start switch make a halfhearted contact and two seconds later the water level has gone down a few millimeters and the switch contacts open again.