Grey water tanks.

[mgibbo]

My 379fl grey water tanks seem to have an issue draining at times. I will open the grey water valves and not much water will come out. If I drive the camper home and open the grey water valves all the water will drain. What could be the issue? Thanks.

[TucsonJim]

I would assume there is either a valve sticking, or an obstruction preventing complete flow.