2003 yam 50tlrb outboard water pump

Have a puzzler. 2003 Yamha 50hp outboard, started up engine and it ran a couple of minutes then no water was coming out of head. Replaced water pump and still no water being pumped. I checked for blockages and ther was none. Old propeller and housing /parts seemd OK but still I replaced. Help any ideas.

BIGE

[boats.net]

The tell-tale hose may be plugged up, remove hose from block and check for blockage.

Thanks
I tried that in fact I ran a hose to the connecter tube at pump housing and water came out at tell tale hose

[boats.net]

If you are running on garden hose flusher then put it in the water and try it.