Freshwater system issue

Thank you! I don't know if I'll make it to the boat this weekend but as soon as I do I'll start there and will certainly let everyone know how it goes.
 
I changed my pump last fall. It's just one big radial feed system, each exit point should be independent off the main feed. The pump can be accessed by removing the tackle draw enclosure under the rigging station sink. Plumbing is straightforward (wasn't too impressed to be honest) but a lot of Ts and connection points. I'm guessing an obstructed or kinked line. There isn't a much of a tie down system either. If a clog look an the connection points. Barbed fittings are used which will restrict ID of the system at these points, that coupled with the barbed end is a good place for things to collect, build up and cause a blockage.
 
I don't have this type of toilet so I don't know what the foot pedal does. Toilet must store water from the low volume sink line and the pedal probably pushes volume into bowl to get a good flush. Just a guess.
A Vacuflush is pretty cool. It is very efficient and uses very little water to flush. There's a separate vacuum system and holding tank that creates vacuum at the toilet. The toilet bowl has a ball valve at the bottom of the bowl. The foot pedal does two things... it is a "handle" to allow water to fill the bowl and then it opens the ball valve to allow the full vacuum force (created on the backside of the ball valve) to suck the bowl contents into the holding tank. Well, technically, the contents are sucked to the vac tank and then pushed to the holding tank.