View Full Version : Yanmar blowing black smoke under load

01-24-2007, 02:43 PM
"Hello, I have twin yanmar 6LYM-STE 350hp in a 52ft power cat. The port engine althou creating max rpm and power is blowing black smoke, a new turbo has been fitted and the boost is good. Four new injectors have been replaced and the other two have been popped tested and appear to be ok (spray pattern is clean) The aftercooler is new.
The fuel injection pump has been sent out for calibration and set back to factory spec's. The inj rebulider has suggested minor fuel adjustment on the limiting bolt, this has not helped no matter which direction I have turned it. Even when cutting fuel back until engine rpm drops and increasing turbo boost, the engine is still pushing out black smoke at 3100 rpm. Injection timing has also been increased by 2 deg with no resolution. Also the air filters have been removed to eliminate any blockage. the bottom of the boat and the props are clean.
If any one has info or insite into this problem it would be greatly appreciated.
Thanks in advance Jim McCauley."

Capt William Myers
01-28-2007, 09:37 PM
I would take a sample of the fuel, I assume you have twin tanks, you may have to much water in the effected tank, or microbes. This may be causing fuel volume flow problems. It would seem from the black smoke that your getting to much fuel, but the fuel it self may be the problem. Run the fuel through one of those large dock side filters they have. Also look at the inside of the main fuel fill line see if its soft and shedding with age."

Joseph Radke
10-31-2007, 10:51 PM
"I would also check fuel filters, you may have a alge build up in the tanks and filters. I just went through this with a 6LP-STE"