Sounds like you have a clog of some type. I would start with tracing the line and flexing it as much as possible to see f that will break it loose.
If that doesn't work, use an air compressor and back flush it lightly to see if you can break it up.
2011 FunFinder XT276
2012 Ford F250 King Ranch 6.7
Native Slayer Propel Fishing kayak
Hobie i9s kayak