Re: Mercury 90hp water pressure problems
The amount of water out the tell tale has very little to do with the water pressure in the engine. All the water from the tell-tale has to go through a thermostat first. Without an actual water pressure gauge you can't tell what the pressure is.
It's possible at idle in cold water that there would be little water from the tell-tale and it would be normal. Also, it's both possible and probable that bugs have taken up residence in that little orifice and partially plugged it.
Is the tell tale real hot? Is there water flowing out of the prop hub? Are the heads too hot to touch without pain?