Ballast bag won't empty

Recently bought an '08 Outback V with the Gravity 1 ballast system. The previous owner never hooked the bag up and never used the the pumps. I finally hooked the lines up yesterday and it filled no problem. I started to empty and when it worked I stopped, filled it back up, kept on going. When I went to empty later that night, it spit out a little and then stopped. The sac will still fill, but will not empty. Any ideas if this is a switch problem or a pump problem.

I'm new to the forums and have found some help here already. Hope you guys can help.

The aerator style pumps have a tendency to lose prime. This happens mostly on the fill pump. The full bag should prime the empty pump just fine. You may need to replace the pump. Is it coming on? (Can you hear it pumping?) There are $32 Walmart pumps that make great replacements for these. I think the stock empty pump is a 500 gph but the Wally one is an 800 so it's actually an upgrade.

An easy way to prime the drain pump is to overfill the bag and make water come out of the drain thru hull. This will push all the air out.

I'll give that a shot, but I can't hear the pump on so I think it may be shot. Thanks for the input guys.

Check the fuse under the dash to see if its blown for ballast drain, if not as Kane said replace the pump from Wally World .