If it's a Jabsco toilet...
The flapper valve is most likely the culprit, especially if you left the toilet is the dry mode for the winter...'cuz that causes the rubber to distort, preventing the pump from priming.If you've been pumping away trying to get the flush water started, you've put a lot of air into the tank, so if you haven't already done so, make sure your tank vent is clear...dirt daubers love to build nests in the thru-hulls. If you didn't thoroughly flush out the tank AND the vent line last fall, check the vent line connection at the tank--the fitting and that end of the hose--and clear out any blockage. Glad you enjoyed my book!