CAT C15 /6NZ trouble continues

when mine was doing it, they suspected a fuel system blockage may have been the issue causing fuel to remain in the head too long and heating up. the cat tech said the 6NZ would go into limp mode when fuel temperature rose above 145F.

 

no problem Dan. do you have the Cat computer display in your truck? I can toggle through a bunch of different parameters on mine, fuel temp, boost, MPG, PTO RPM, oil pressure, cruise settings, intake temp and more...when they told me it could be boiling fuel I switched the display to fuel temp and could tell them that wasn't the issue because it would be missing well below the 145F threshold so it wasn't a derating issue from the fuel temp.

 

I don't think I've ever followed a thread with this much... I don't even know what the word is but I'm completely certain you are going to find the answer to this.

I can't contribute anything mechanical to this conversation, electronics are certainly well beyond the scope of my knowledge or interest. So I can really only offer you support. But I'm glad that you are here truck 307.

On this site there are guys that are absolute experts with those engines and problems and guys that just have so many years of experience, so I'm certain someone will be able to help you or guide you to someone that will help.

 

Dan starting this thread with his issues saved me about $20,000. we have been in contact here as well as by phone for about 2 years now. if it wasn't for him, I would not have known about the reman injector issues back in 2012. presenting his information to my local Cat repair shop made them acknowledge there was in fact an issue, and got them to warranty a new set of injectors with my engine 2 years beyond the platinum warranty period, which lead to them also provide me with a new reman head after discovering faulty injector seats from not being machined properly. I am forever in his debt, and will do whatever I can to help in solving his 6NZ issues with any info that may be helpful.

Thank you Dan. I'm sure you have a lot of guys watching and hoping for a resolution.

 

Overheated fuel wouldn't have crossed my mind. Since @maggard359 has had experience with it I will toss this out there. At one time there was a problem with the return line out of the head. I don't know if that line is supplied by Cat or the oem. Either way it has been known to create issues. I would remove it and check it specifically as it is subject to the hottest fuel. I would also see if I could blow humanly blow air back to the splitter valve. Warning! California says blowing on fuel lines is hazardous to your health. But alas so is losing your mind over a very annoying truck (engine) issue.