Turbo lag

BIG CAT said:

the boost reference tube gets filtered air from the intake side. its unlikely to be plugged up. but there is a real possibility of a rust hole. mechanical damage is unlikely unless someone has been doing work on the engine in that specific area. but even then those tube are usually pretty robust and would take a heck of impact to kink it.

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"the boost reference tube gets filtered air from the intake side. its unlikely to be plugged up"
I have seen a couple of cases where the turbo shaft seals were losing oil a bit and also where the engine blowby was routed back into the air cleaner allowing some 'slop' of oil and water to enter the tube area.
YMMV

Do you have electronic throttles?
Do you use them synchronised?

No electronic throttles or Synchronizers. And thanks folks. I have not been able to get down there to troubleshoot. The weather here has been horrible...along with other things getting in the way. Hopefully get down there this week.

Black smoke equals soot equals unburned fuel which the aforementioned turbo lag would actually replicate, which you do not have. If your Cummins engines have electronic controls (as opposed to the older mechanical injection pump) then they are programmed to ramp the fuel in proportion to the boost pressure to avoid the soot (emissions). I could be missing something here but I would recommend you determine whether your engines are the old mechanical fuel delivery type before you go possibly chasing your tail on an electronic sensor problem. If there is an electronic engine controller mounted on the side of the engine then someone with the Cummins software can go online and read every parameter that controller is looking at to decide how much fuel to feed.

tbwil1 said:

I could be missing something here but I would recommend you determine whether your engines are the old mechanical fuel delivery type before you go possibly chasing your tail on an electronic sensor problem.

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You are definitely missing something. Cummins 330B is a mechanical engine. Maybe I should use the proper official name of 6BTA 5.9 M3...or something like that. The similar common rail electronically controlled engine nomenclature is QSB 5.9.

I am fairly well versed in the operation and mechanics of this engine. The one thing I have learned in this thread is the boost "sensor" going to the injection pump. I put "sensor" in quotes because it appears to be mechanical in operation with an aneroid sensing the boost pressure and adjusting fuel based on boost pressure as the engine comes up to speed.

I did not see an indication of the age of your particular engines so I had no idea of the controls. I worked as a Cummins power tech on backup power systems till I retired in 2010 so I "assumed" they were equipped with the engine mounted ECM. My apologies for butting in.

tbwil1 said:

I did not see an indication of the age of your particular engines so I had no idea of the controls. I worked as a Cummins power tech on backup power systems till I retired in 2010 so I "assumed" they were equipped with the engine mounted ECM. My apologies for butting in.

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No apology necessary and you certainly weren't butting in. My apologies for not being more clear! I think most of us have been onhere for quite awhile and have a good idea of the boats and engines we have. I see you are new...welcome aboard. And another apology if I came off as harsh or not very welcoming!! Stick around and have fun. Your expertise will be greatly appreciated!