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New Vacuum pump installed, instant black smoke/ loss of low end power ???


New Member
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2002 LB7 completely stock. has always run very strong. original vacuum pump ( California emissions system ) started knocking loudly so i had it replaced at a local shop. the truck now runs like it always has in the morning until it comes up to operating temp. and then looses power in 1st through 2nd gear shift with HEAVY BLACK SMOKE. ( this truck has never had black smoke ) running third through fifth gear is strong as usual. can the new vacuum pump cause other sensors in the emission system to fail ??? little help here please


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Miles City, Montana
Oh wait, this is a Duramax LB7, the below info may not apply. I just reread Your posting above and realized it warnt a 6.2 or 6.5

Remove the vacuum tube from the waste gate actuator and check to be sure it moves freely.
Need to do some vacuum checks, check vacuum pre solenoid then post solenoid while driving and under a load.
On post solenoid check, install a T either at the WG actuator or else right past the solenoid and run a long enough vacuum hose so You can observe vacuum while driving.
I am guessing though, that it is a solenoid issue, dont just fire the parts cannon at it hough, do the checks and diagnostics and replace components as needed, only with original Delco units.
I always pack a spare solenoid and a baro sensor with the truck. I also have a home made manual waste gate controller that I pack along too, just in case I am far from home and the spare parts dont fix the black smoke.


Well it hits on 7 of 8...
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Take it back to local shop and give them an opportunity to correct their screw up. They may have left something disconnected like a intercooler pipe etc.