Ken Hughes wrote:
Now, I gotta believe that the toilet fill valve
(controlled by the solenoid?) is open - causing the pressure pump to run
continuously.

I just took a look at the drawing..I should have in the first place (red
face here), 'cuz it's not the type of solenoid valve I thought it
was...it's a water valve that opens and closes kinda like an
electrically operated faucet. In installations that use onboard
pressurized water, it just opens and closes to block or allow the flow
of pressurized water already in the hose...but if, when a sea water pump
is used instead, it starts the pump, you're prob'ly right--if the valve
is stuck open, it would cause the pump to run when the breaker is on to
supply power to the system.

And, if that's the case, sea water mineral buildup could be the culprit.
Try removing the valve (take a look inside the hose when you do...'cuz
if there's buildup in the valve, there most likely will be in the hose
too) and soaking in it a 12% solution of muriatic and water for 30-45
minutes--no longer may dissolve it and solve your problem. If not, a new
valve is prob'ly the answer.
--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html