did i say that power loss to the pump wouldn't stop the turbine?

the question asked was what is the purpose of the solenoid, so once again, the solenoid provides a means of immediately stopping fuel flow to the turbine. shutting off the power to the fuel pump doesn't immediately stop the flow of fuel.

if you don't believe that take a fuel pump and prime it, use a AA battery and pulse the pump every 1/2 second by contacting the battery to the leads on the pump, the stream of fuel out of the pump will be a steady trickle, do the same to a solenoid and it'll be a broken stream.