Why does your car blow white smoke and then not start?

white smoke is caused by 2 different things either too much air not enough fuel or you have a head problem and antifreeze is leaking into the engine block. to check for a head problem is it always running low on anti-freeze or if you look in the surge tank do you see aloy of bubbles? as far as the air fuel you can open the injector line and see how much it is pushing out and listen for cracks that are sucking in air on the intake