Fuel- High pressure relief valve

[JMBT]

I guess I don’t know how else you would diagnose the relief valve?? Cummins fault tree for 3727 just says replace it. Code 3727 says the relief valve has tripped at too low of a pressure, not too high. Cummins apparently interperets that as, it is faulty, and must be replaced, (or can’t be trusted). I guess it could be just Cummins CYA, but I am open to other suggestions if you have some.
I agree the pump could be leaking even though it is new. Many new parts these days are crap. And from my experience the 2 cylinder pump “upgrade” is junk compared to the old three cylinder. They should have just made an update kit for the old three cylinder, but....that wouldn’t make mother Cummins $4600 a pop. I really think there could/should be a class action lawsuit associated with all the engineering F-ups on the 2250’s and 2350’s.
That being said, I don’t think high return flow or a leaking injector would set code 3727.