Honda BF75 running on Flush Port

My Scout is now in care of my Grandson. He had a low battery on the trailer and jump started the Honda BF75 [1996] only using the flush port. I know the manual says this is not to be done but here is my question. He got caught in the bay with an alarm and we are thinking it is the impeller. Originally we thought that if we saw the pee stream when started on the flush port the motor and impeller were receiving water but after some thought realized that, formerly [engine off] when I flushed the boat after a trip using the flush port, I would also get a pee stream. Made me think our conclusion that impeller was getting lubricated was incorrect. If he jump started the boat on trailer on flush port and let it run too long that could have ruined the impeller. What do you think? [we are hoping that is the case because an easy fix and it has been a while since replacement]

Yes, you probably have a damaged pump due to overheating the components from water starvation. I would recommend replacing the pump using the COMPLETE KIT that is available rather than just the impeller alone.

Remember, the pump is designed to pull water in at the bottom through the intake ports and PUSH it upward into the engine. So, even if SOME water was making its way DOWN the water tube to the pump, the action of the pump would be trying to reject it.
Therefore, you know that the pump was starved for water as long as the engine was running.

Good luck.