Johnson 9.9 repedative water pump issue

i have a 1989 9.9 changed water pump great flow next time out went to use not working could being bounced around with my 50 hrs in rough seas cause something to make it not work

Those pumps are very reliable.----Good for about 5 seasons ( impeller ) with no issues.-----When you tested in a bucket was water 8 " above impeller ?------And what boat is it on ?----A sailboat ?----Is this a long shaft motor ?---Is water intake screen clear ?-----Describe rough seas..------I have done lots sailing in waves up to 8' or 10'( 3 meter ) and do not consider it rough.

its on a 16 ft with a 50 hs went to flush just cause we were in salt didnt run it in the salt had the muff on with hose started it no flow did the same thing before we changed it i was thinking that bouncing around at top speed could have caused the little pin for the impeller gets banged out of place out of place the old water pump when we took it off the impeller was fine but didnt flow and its a short shaft and rough seas 4ft on the ocean heading in we got banged up running at full speed 25 ml a hour with the big motor not the kicker

That little pin to drive the impeller stays put in all conditions !----Are you using factory parts or something else.-----Have you verified that the tell tale hose and fitting are clear ?

it worked when i put the new impeller and had a very strong flow and it was the johnson kit new cup everything

Those pumps were used from 1974 to 2007 models.------Therefor it is a good reliable design, yes it is !!-----I have numerous examples of these 9.9 / 15 HP models.----Just took one apart this afternoon for inspection of pistons / rings.-----I can not see your motor or what you have done.------I suspect a blockage somewhere in your cooling system.