Excessive Black Smoke

[zark123]

Excessive black smoke upon accelaration.Service engine light on.5 lbs. vaccumm @ 3000 rpm.Waste gate free,2 lbs pulls open vaccumm pod. Seems to have less power.124,540 1997 2500.Fuel mileage @11 to 13,poor at it's best.Sure do like them non-computor trucks.

[rameye]

If I read corrrectly you stated .5 lbs vaccuum @ 3000 rpm

you should have atleast 15 inches of vaccuum at the intake to the vaccuum pump.(hose behind ac compressor)

what is your boost like??

[Marty Lau]

I'd bet a buck that your vacum system has a problem either leak in line of pump is gone. A lot of us have trashed the vacum systme completely and replaced the vacum wastegate control with a TurboMaster or DIY version of it.
It can cost you as much or more to fix the vacum sytem. I did it almost 2 years ago and removed vacum pump and put a 1993 belt on and life is good. The black smoke is a sign that you have unburned fuel in exhaust.