F-250
 

So my wife is freaking out that our truck is rolling coal ((we don't have a smoke switch, nor a chip) she had a friend test the truck and he is saying it's some sort of a pump that comes over $1,000 for the cheap ones, but he won't tell me which one, it's dark smoke, so me I'm not worried about it, but it smokes the whole time my wife drives it. I know the fuel, steering & coolant pumps just got replaced. So my question is... Is it a pump? A fuel injector? Or just builtup junk? The engine gaskets blew at 140,000 miles, so just about everything is new. Bulletproof kit, new steering pump, fuel pump, new filters, new headers, head studs. The engine is completely rebuilt with new parts

Rolling coal usually implies the engine is getting more fuel than it can burn for the amount of air available, aka overfueling. It could result from an engine management problem including a chip that overrides factory specs; a failing engine component such as a fuel injector; a turbocharger that is failing or too small for the amount of fuel it needs to handle, etc.

I'd want to find out why, if for no other reason than because the black smoke is unburned fuel that you bought and paid for, and are throwing out the exhaust pipe. If the truck has an EGR valve, that might be a place to look, too.