Mercury 30 Jet not peeing stream at high speed

[bgtuc84]

Hi all. I have a 1997 Mercury 30Jet. It pees at idle and low RPM. As soon a I throttle up to high RPM, water stream goes from solid stream to steam to non existent. The water pump has been replaced along with exhaust gasket and water tube intake gasket. I was told the woodruff key was replaced and looks good. The motor is set to the correct height as this was not an issue in the past - plus the boat has a tunnel. There is no thermostat on this model. No motor alarms are going off. Any suggestions at this point help.

 

[Texasmark]

If you are going to steam, you are running over 200F. Warning systems activate at 195F on my engines. Did this occur immediately after the maintenance action? Sounds like you have some blockage in your water pickup somewhere.....did your old impeller have chunks of blade missing? Any history of overheating prior to maintenance action? Maintenance action not performed correctly possibly. You run over a sandbar or something that could ingest debris that would clog passages...weeds, water Hydrilla, Cattail Moss, shallow water operation picking up sand or mud........ Just some thoughts.

 

[faztbullet]

the 4 or 3 cylinder?// Should be 4