Trying to find out how common this is. 2nd season my water pump could not draw water during initial season launch. Disconnected hose at the thermostat water input last season. There was a hissing noise of escaping air, and then water started flowing. This year, both engines acted the same way. Disconnected the hose from water input at water pump. Held hose below water line and water strated flowing. Last season I started a test with Globe Run Dry impellers. That was the first time it happened to one engine only. Wondering if this could be a result of Run Dry impellers not having enough suction to start from initial season launch. The vessel is launched from a trailer. The mechanic said the water line from seacock had to run over a stringer before it entered water pump. Opined that left too much uphill draw to get water at water pump location. He recommended new impellers every year. The Run Dry impellers could be at fault, but if I did not have those in, the standard impellers would have been smoked by the time water started running. Is this common? Is it an impeller issue, or a water line issue? Any thoughts on mitigation? Thanks for comments. Hope Viper sees this. er