Df140 Buzz at idle/low rpm at back of motor

[Velzynh]

Hi. I have a 2011 df140 with 1400 hours.
Engine runs fine at all rpm but recently when at idle or real low rpm has a buzz type noise from the back of the engine. Kind of like a real muffled engine alarm buzz. As best I can tell it is in the fuel rack/injector area. Could this be an injector? If so any idea why it is causing this?
Thanks
Ryan

[macedonia]

Interesting issue. The only thing that comes to mind is that the high pressure fuel filter should have been changed at 1000 hours (at least on my 2007 DF140 engines). Did this get done?

[Velzynh]

Engine is new to me. It was supposedly well taken care of before me by a commercial fisherman who trailered it. Everyone says that though right? I'm gone for a week but take a better look at the engine when I get back