Black fuel filter(pics included)

The top of ring on the injector stops the oil from draining down from the head. If the o ring fails thats how oil gets in to the fuel. This can happen with any diesel engine. If your tanks is clean than sounds like your fuel lines are coming apart.

 

I've seen this numerous times. Also a leaky injector over night dripping down on piston and past rings. But that normally comes with a hard start condition.

 

Can be from the chemical properties of fuel, and from over heating diesel to.

 

The pics looks like there’s some trash in the bottom. Could be lines coming apart. I’m surprised though, Trucks not that old. I’ve had mine look terrible. Black, algae. Even had them filled with Rusty looking water, when changed. Bad fuel? Sabotage? I don’t know. I did replace braided tank lines going to gt splitter valve, soon afterwards, with super duper expensive heavy duty lines. Also replaced the other braided lines. Can’t remember when though. Hate to see you throw parts at it. But maybe just replacing the line from splitter valve on top of tank to the filter, to eliminate it, wouldn’t hurt. I had an o ring fail, only about 7 yrs old. Changed injector, still don’t know if the injector itself was bad. A leaky injector cup, would make the fuel in tanks black also. If it’s clean, must be coming from the lines falling apart. The ones from tanks to splitter valve, if changed, need to be kept the same length and routed the same way, avoiding any high loops, that cause a lost siphon. They need to be the same lengths, from each tank, and ran on a constant rise from tanks to valve. Supply line to filter needs to be higher than the others from tanks. It’s a job changing them all. I suspect the supply line from valve to filter, because it’s probably subject to heat.

 

I just realized, what you’re seeing is the filtered fuel. Might not be noticeable in tank, but once it’s filtered the trash shows up.

 

Hopefully you can send a sample soon to lab and get a definitive answer from analysis