1994 Mercury 150 hp EFI stopped peeing water from the tell tale. Did not overheat. Dropped lower unit and replaced impeller (which was original - low hours on motor). Gaskets and plate also replaced. Old impeller looked ok (no pieces missing) Blew air thru cooling system from water tube and air came out tell tale hole. Also put air into lower unit pick up using hose attachment over water intake and air came out at inlet to water pump (with pump housing disassembled. Put all back together and still no water coming out tell tale or any where else it shouldn't. Disassembled again and rechecked everything, reassembled and still no water.