Need help - air bubble puzzle

[wengxyu]

There has been a weird issue with my pump. The issue was definitely not there a month ago when I open the pool. I am not sure if anyone has experienced this before.

When the pump valve is on the skimmer size, there are many small air bubbles coming out of the return line and the pressure fluctuate between 2 and 15 psi.

When I rotate the pump valve to in between skimmer and main drain, the air bubbles seem to disappeared and the pressure is normal.

When I put the pump valve on the main drain side, there is no pressure at all no matter how long I wait.

I am really confused now. :grrrr:

 

[treebeard056]

I'm no expert, but sounds like you have a blockage on the man drain side - Does the valve feel like its functioning right?

 

[JohnT]

It sounds like your pump isn't able to pull enough water from the skimmer alone or main drain alone to maintain prime. Is your water level high enough? Any chance you have a clogged skimmer basket or have you vacuumed without the basket in place?