K,

You mentioned in another post that you had a lot of debris from a storm, including oak balls.

I am wondering if there is a possibility your main drain could be partially blocked internally and starving the pump as Poolsean mentioned.

If you can find a way using a garden hose to positively identify the skimmer and main drain returns, it will help enormously.

The other possibility is that the pump is losing its prime by not being able to overcome the suction head needed for it to operate.

This now mens you have to rent a submersible pump, and leave the pool pump shut off.

Hope this helps.

Pat