Also, do not "fishmouth' the vent tube, leave it open. You should have as much flow into the tank as a vent, as you do for fuel to leave. There should be no undue pressure differntial. These turbine pumps draw fuel at a much higher rate than what you are used to on a glow or gas engine. I have seen a similar thing happen with a plugged vent line. The turbine would shut down when the throttle was increased, but then would start back up, since by the time you got around to starting it again, the pressure would have equalized in the tank.
Sounds like ou are on the right track though.