how to test a crank sensor on a chevy suburban 5.7?

[amanda]

i think my crank sensor is acting up . car will not start and when i let go of turning the key it's like then it trys to run and back fires from the in take and i can see the smoke. i removed the crank sensor and when i do the fuel pump runs for a sec and when i reinstall it ( with the key on position ) i hear the fuel pump turn on and i can hear the motor get fire to 1 cylinder and the motor will move without me doing nothing but putting the connector back on . i have never seen a car get spark and think the crank sensor is faulty please help
i used carburetor cleaner and it did not make a difference i think i will buy one from auto zone and use my old o-ring on it and see if it works ( money it tight ) and if it works i will clean and paint the old part and put it in the box and take it back for my money lol it has had hard starting everyday and it will take 2-3 times trying then it will start , fuel pressure is perfect , just hope it is not the ecu i need to get back to work , this suburban broke down 3 time this week , first 1 wheel bearing locked up the wheel and that was a job to get a self welded bearing off 5 hours and next day the other bearing went out so i was stuck again in the cold yelling at the tire . today the bolt to the starter broke off in front of my kids school ,then after drilling the broken bolt out the car wont start , man what a week i need a beer thanks for your help