Fresh water flush problem on 2004 300 HPDI

[Jaxdiver28540]

I have a pair of 2004 300 HPDI's. With a regular garden hose to the starboard fresh water nipple, I have a normal flow of water out of the the pee tube. When I connect to the port engine, sometimes I will not have any flow at all or maybe a dribble. I recently have had the water pumps and thermostats replaced on both engines. I still have the same issue with the port engine. I have checked and there in no kink in the water nipple hose. I have removed the 1/4 hose from the pee tube outlet and tried flushing, but with not much results. When the boat is under power I have strong flow from BOTH pee tubes and the engine temp is normal. The issue is only in the fresh water nipple flush.

Any suggestions how to "clean out" the fresh water flush system to where the discharge is back to that of the starboard engine??

[boats.net]

Check flush hose for blockage.