Does ULSD clog up your cummins N-14

its the fuel, but have you checkes for boost leaks like a bad charge air, or bad boot. Does the boost seem as high as it always was?

 

I have to admit, if there was no problems with the fuel, I would be looking elsewhere, and the charge air cooler would be the first place I would be looking at. A leak there woud do it and it's so gradual you would never know it. And you can't tell just by looking, since there is no load and no real amount of boost while sitting still.

You haven't been in to Cummins at any time in that time frame and allowed them to reset the computer for emissions purposes, have you? They have a tendency to "update" and it can cause a drop off in mileage traceable to the improved emissions.

If everything else in the engine is good, then I would get hold of the boys at Pittsburgh Diesel and have them check out the engine. If it's happened to a Cummins, they have probably seen it before.

 

There is a slight decrease in available BTUs from ULSD, but you really shouldn't notice it.

Have you checked the airfilter? Did you blow back through the fuel lines into the tank (plugged pickup?)?? Checked the exhaust for pinches/restrictions (such as a internally-failed muffler)? And just because a sensor "reads" good, it might be on the "low" side of its optimum range.

I'm not sure the older engines are capable of the injections pressure the newer "common rail" trucks are producing...and that might be the difference.

I saw an improvement running ULSD in my pickup, but it was designed to run the ULSD.

ULSD will "scrub" the fuel system, it will mobilize things that were floating around the system.


steved