2002 Chevy Tahoe testing crank shaft position sensor

My 2002 Tahoe 2wd a/t 5.3L just stalled the other day with now warning. I suspect it is the fuel pump but I want to cover all bases. I listened to the fuel pump with key on engine off and it does not make the normal whinning noise, more like a thuthuthu. I want to test the crank shaft sensor to make sure that isn't the culprit before attempting the pump. What is the procedure for testing the sensor and the specs. Also tested tested the fuel pressure at the fuel rail and shows no pressure.