2001 Silverado 5.3 started blowing out black soot upon start up

[castmaster]

Started my truck this morning and it blew out a couple of spots(maybe 3" diameter) of black sooty looking stuff, and seemed to have some condensation along with it. Never done this before. Is it just some carbon buildup that was loosened up and went through the exhaust or is it something to worry about?

Motor is a 5.3 Vortec, 2001 Chevy Silverado.

[Big Buck Buster]

Have you recently had any problems with the way it ran, or had a fuel pressure regulator replaced because of leaking/hard starting, or any other issues causing it to run rich?

Sounds to me like it is just carbon letting loose in the exhaust. The moisture is normal. The cat is doing its job if you have moisture dripping out of the tailpipe. That is what the cat is doing with the exhaust gasses, turning them into H2O(water).

[castmaster]

No it has ran normal just like it always has. No trouble with starting, idles smooth, no haven't had a fuel pressure regulator replaced. I did run the truck from Hastings to Moorhead and back yesterday, about 650 miles round trip so maybe that loosened up some carbon?

[deadeye]

That would be a good guess. If you go on a long trip it might have gotten the exhaust hot enough to loosen some of that carbon up.

[jeffreyd]

or the gas you bought had some water in it. it could have washed down the carbon and collected in the muffler. then when you start it will pop out the rest of it.