I WORK ON CUMMINS DIESELS, YOU MIGHT HAVE A INJECTOR HANGING OPEN JUST A BIT, TRY SOME POWER SERVICE FUEL INJECTOR CLEANER, THAT IS WHAT WE USE AT MY DEALERSHIP FOR CUMMINS DIESELS, I ALSO USE IT IN MY CUMMINS DIESEL, BUT SOME BLACK SMOKE IS NORMAL :!: :!:
''JUST MY TWO CENT'S WORTH''
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