Black smoke on startup

[kcv67]

When I sart the truck after a couple of days it smokes black for a bout 30 seconds. I havent lost any fuel mile age or performance it just puts out a lot of black smoke. Could it be the overflow spring?

 

[dseabaugh]

black smoke

Mine does the same thing for 5-10 seconds after startup, even when warm. When I take off with a load it smokes black like It is running on coal if I put my foot in it till it is warmed up. I would like to know also.