hi all I have a 2005 Mercury Optimax has done now 1600 hrs previously haven’t had many issues with it but I am stumped on this one. I have smart craft gauges and an alarm comes up saying water pressure sensor failur. I have replaced the sensor now3 times and every time I change it it works for a few hours then slowly you see the water pressure start dropping on the gauge till it gets to zero but the tell tail is pushing lots of water.
I am sure it must be a short somewhere as the sensor eventually stops working and it goes into guardian mode and restricts me to 65% throttle so I can still get on the plain but can’t go over 4500rpm
has anyone had a similar problem. I have a brand new gearbox on so water pump is not the issue as problem started before I replaced the gearbox