Toilets designed to use pressurized fresh water don't have an intake pump...instead there's a solenoid valve--either built into the toilet along with the necessary vacuum breaker and backflow preventer valve, or installed in the intake line from the cold water line to the head
sink. The solenoid valve--which must b wired to the flush button--acts like a faucet...opening to allow pressurized flush water to flow, closing to block it.
Circumventing the fresh water pump
is the last thing you should do because that wouldn't provide the protection from bacteria in the bowl migrating into the fresh water plumbing
that pressurized flush water and solenoid do. And you'd still need the siphon breaker and backflow prevention valve.
Jabsco does offer a fresh water conversion kit for your toilet (37245) and it's the safest way to do it, but that kit is expensive...best price
I could find was $499 at Defender. You might be able to offset the cost a bit by selling the remote
intake pump and sea water pump and motor
assembly...or you could re-purpose the intake pump to be a washdown pump.
I'm sure at least a couple of people will reply with instructions for a DIY
conversion. It's something that every toilet mfr strongly recommends against, but it's your boat
, your money
and your decision.
Just saw your post re solenoid valve...
Any solenoid valve in a sea water toilet would be on the vented loop that should
be in the intake line between the pump and bowl on any toilet installed below waterline.