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GMC Repair/truck is putting out black smoke

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Expert: CAJUNSC/RAMBLER390 - 7/29/2009


Question
I have a 2001 4x4 with a 4.6 motor.I recently cut the cat- inverters out .My problem is every now and then the truck loses power and the check engine flashes a few times and the black smoke pours out of it .It might happen a few times one day ,not very reguler...A friend checked the code and he thought?? that it was running lean on a couple of cylinders..It almosy seems like its flooding

Answer
Hi-
What was the code? p0174? or p0171?
I would check the fuel pressure rguulator (small round regulator located on the DRIVERS side fuel rail, underhood) Pull off the small vacuum line off the regulator, if there is ANY gas in that vacuum line, that is your problem.
Also if the converters were cut off  and NOT replaced, you may have the o2 sensore sending low readings to the computer, and the computer is trying to falsely enrichen the mixture.
Thats my best advice with information given.
Thanks
Pawl

GMC Repair

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CAJUNSC/RAMBLER390

Expertise

1998 and NEWER questions ONLY!! I WILL REJECT QUESTIONS FROM 1998 BACK. Electrical diagnosis. Brake Diagnosis. Driveability, Service Engine Soon Lights. Engine mechanical. Automatic or Standard Transmissions. Drive Line (drive shafts, axles) Rear and front differentials and 4wd Transfer Cases. Tires and wheels. ABS. HVAC. Air Bag (SIR). Interior, seats, etc... 6.6L Duramax Diesel diagnosis. 6.5L diesel diagnosis. I WILL not answer Alignment questions OR carburetor questions.
I need YEAR, MAKE and MODEL of vehicle, and ENGINE SIZE and TRANSMISSION type, IF applicable to the question. The more information, the better.
EFFECTIVE Jan. 2012, I will not answer questions about PARTS or AFTER MARKET installed items.(After Market radios, entertainment systems, alarms, etc...)
I work at a Large, Busy GM Dealership
Last thing, my answers are JUST SUGGESTIONS and ADVICE and you should ALWAYS CHECK with your mechanic for proper diagnosis and repair.

Experience

18 Years GM Dealership experience as an "A" line tech. ASE Master Technician. A-9 Light duty Diesel certified as of 2011. 100% GM certified MTC Certified. GM World Class Technician.

Education/Credentials
High School graduate. No College or higher learning.

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