AFC Top/Banjo Bolt Black Substance

[matthewh]

Working on installing one of Erics fuel pins. To my knowledge, the pump has never been into, and it shows. Unbolted the AFC fitting, swung it out the way, and removed the AFC top. I noticed the AFC banjo bolt has a black substance, almost like soot on the end of it, and the top is black, mainly where the boost comes in. Its not gritty, you could smash it with your finger, but it looked like soot.

So, I though it was just a reference line to signal boost and push the pin down. What/where would this black substance be from? Turbo failing? Something internal leaking? Truck has 107xxx original miles on it, guy before me towed a fifth wheel camper all over