I have an 03 LSV and had the same problem.....not anymore.

I'm not sure of your set-up but I had two drain pumps that fed to one thru-hull. The two hoses combined and then were pumped out of one hole. My bags were very hard to drain and I spent a lot of time lifting up on the bags trying to get the pumps to pick up. I would eventually muscle the bags over the edge and pour them out manually.

The first thing to check is obviously the pumps. Take them out and test them in a bucket of water to make sure they are pumping correctly. Second, check the lines to see if there is any trash. Lastly, check the power to the pumps from your switches....make sure you have 12-13 volts going to the pumps. I did all of this.....still wasn't pumping out correctly.

So....I drilled another thru-hull in my boat. Now, my left bag drains to the left and my right bag to the right. I separated the bags to drain independently and I haven't had a problem since. You still have to make sure the pumps are primed but I don't muscle the bags anymore.