Morning. Engine Ser. No. is 0T148359. This problem has been happening for a couple of seasons. Two shops have failed to find source, my turn I guess. Oh, new impellers/water pump kits made no difference, but I'm due for one now anyway.
After running at or near WOT for several minutes, slowing to idle will usually trigger a constant alarm and activate guardian mode. Shutting down and restarting a few times gets me through the 'no wake zone' or whatever, until I can get back to higher rpm. Always have water streaming from telltale, pressure at WOT is about 15psi, pressure at idle barely registers on guage, but I guess that's normal - a couple of psi at idle.
The thermostats do open around 130-140 deg based on stove top test - I'll replace anyway. I'm wondering about the temp sensor and the popett. If I understand correctly, a stuck popett will result in little or no water going to block via the thermostat path. Stats are at the No. 1 and 2 cylinders. The single temp sensor is at the No. 1 cylinder. So a faulty poppet could prevent cooling water from flowing correctly at low rpm? A warm engine and reduced cooling water produces alarm at low rpm, yes?
Regarding the popett. I read here that you have to disconnect almost all of the wiring on the right side - I see that - but what about the trim switch on the bottom cowling, which will not slide back through the bottom cowling. Do you have to cut and splice those wires after?