GMC Repair: engine problem, air leaks, gmc 3500

Question
I have GMC 3500 turbo disel 2000Y and few days ago i started to hear strange sound and noise from my engine,black fume is going out and when i just start engine it doesn't sound idle when i start to drive just i push little pedal it lucks that i am going jump and sound from engine is like that i am driving 50/km/he.
Please tell me what can be problem because my mechanic told me that is pump and indjectors.Thank you


Answer
Hi
I would have them first check for air leaks.
If it has a high revving sound while driving, I would check for air leaks.
I would observe the balance rates on the scan tool.
Any balance rate too high, would be injectors.
Please follow post back with balance rates, if possible.
Hope this helps
Pawl