2015 D13 losing fuel prime randomly

well if you replaced all cups than you replace injectors as well, it could be fuel filter housing causing this or also maybe need to open up and look at injectors again fuel valves either fail or dont nothing in between.

 

the only other thing i have seen is a few times is a broken injector doin exactly same thing like what you are descrbing and it makes the problem when it feels like.

 

yes like cut in half physicaly broken, i've only seen it twice, if you take them out again send me pic of injector tips and i can tell you if you have a problem or not.

 

did you do this job yourself or a shop? I replaced the cups not the injectors, problem went away for a couple of days and came back with hard starting, Changed the pressure valve at front of engine and no difference, pressurized the fuel system with air in tank and found no leaks. Looked in fuel tanks while truck running and saw air bubbles meaning the cups or injectors are the culprit. Before I did the cups, the truck would start every time no problem, tried for 3 days. Went ahead and changed them anyways. If you have good power under load, I would just install an electric fuel pump for priming before starting truck, similar to a cummins with electric lift pump but you can get one and install inline anywhere, almost. Hope helps.