Hi, and welcome to the forum. I honestly don't know what he's talking about. Never heard of a solenoid valve. The only solenoid, that I know of is in the starter circuit.
Could it be something with the fuel injection? I'm afraid the my knowledge is somewhat lacking when it comes to fuel injection systems on SeaDoo's. Call your mechanic and ask him to elaborate. I guess a fuel injector could be considered a solenoid valve.
Lou