Water pressure line plugged?
 

This past weekend when I started the motor and pulled away from the dock that the water pressure was zero. I checked my through transom dump and water was pumping at what seemed to be a normal amount and the temp was normal. I eased on plane and the pressure guage didn't move. I stopped and shut the pressure control off to see if that would help and tried again and the gauge still read zero. Finally I decided to just go on plane and watch the temp. I drove around for a couple minutes and the temp was fine, and the pressure was still not reading. Finally after cruising a few minutes the guage started to read and the pressure seemed to be back to where it is supposed to be with the dump valve completely shut. I then opened the relief to the previous setting and boated for the next 4 hrs with all systems go. I probably made 10 passes at WOT and the pressure and temp were perfect. Has anyone seen the small hose used for mechanical pressure guages plug up and cause the guage to not work? I trust my guages, but find it strange in this case that the pressure was zero, but the temp never went over 150 after some cruising and then was just fine. Maybe the obstruction in the pressure line worked itself out and allowed the guage to work?? What do you guys think? Thanks Craig

My lines are connected to the block and they plugged up 3 times this year. When they start acting up, disconnect form sending unit and let clean water run through line and into a bucket or over board.

For that exact reason I moved my water pressure tap to the top of the engine.... it would continually stop up from sand or scale. One time it packed crud into the line 3". The answer is YES! But don't even think about an electric sender as they are not rust proof and will fail quickly.