Thanks again Peggie. Turns out the fix was simple. One of the power
leads to the solenoid was loose. Just needed a new crimp and all was well.

Peggie Hall wrote:

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.