I just purchased a 2005 Suburban with 5.3L. I've noticed on occasion I get white smoke and strong fuel smell at startup at tail pipe. Usually worse after shut off for about 2-4 hrs. Not as bad after sitting overnight or days. Also, after initial puff of smoke, I get a very steady consistent white smoke (looks like vapor) until the engine reaches normal operating temperature. I get lots of water from the tail pipe until it reaches normal temp. No coolant loss or sweet smell of antifreeze. Could this be a leaky fuel injector? I haven't checked fuel pressure yet...I thought I'd ask on the forum to get a feel if anyone else experience this. By the way, fuel economy is okay...about 16 mpg, power is great. I thought the puff of smoke could be leaky valve seals, but the smoke is white (not blueish). One final note....when engine starts...I hear a slapping sound for a split second, on occasion. I'm thinking flooded cylinder due to leaking injector. What do you guys think? I can afford mechanic...I have to do the repairs myself. I'd like to have a well informed approach rather than replacing this, replacing that! Any feed back is welcome! Thanks!