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About Todd Puccio
Expertise
General auto repair,electical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm spacific. I have worked at my current dealseship since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way.

Experience
Experience in the area:I have been employed by the same Gm dealer for 18 years and and a ASE master technician. I work at a Pontiac and GMC truck store. Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franschise was purchased by this dealership. Organazations: ASE master techncian Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied scineces (auto technology)Awards and Honors: GMC master techncian

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Pontiac Repair - black smoke when car is started

Expert: Todd Puccio - 10/24/2009

Question
I have an 86 2.8 Firebird. It will start fine then after it is driven a bit and shut off, upon restart it will be hard to fire and belch black smoke out the tailpipe. I do notice it takes a long time to warm up. I know the MAF has been replaced recently and im going to replace the O2 sensor. This problem only occurs after the car has been driven a while. Could the coolant temp sensor be the culprit or maybe a leaky cold start injector? I know a good bit about EFI but im stumped on this one.

Answer
Hi steve:

well all of the parts you menntioned except the O2 sensor can cause this issue. It may not be a bad idea to replace the o2 sensor anyways being that the car is 24 years old! but my guess here would be either a leaking injector(s) or cold start injector leaking. the only real way to find it for sure is to get the engine hot then take off the upper intake manifold and leave the fuel line connected and put a piece of paer towel under the injectors including the cold start injetor and then cycle the key a few times to prime the fuel system and let the car sit and if you have leaking injector the paper towel will be wet under the one(s) that are leaking. If you have a fuel gauge put that on too and see if the pressure bleeds off rapidly You could also have a vapor lock condition here if the pressure bleeds of back into the tank rather then into the engine. What happens is if the fuel is not under pressure and on a hot engine the fuel that is left in the rail will vaporize and when you try to start the car your getting fuel vapor at first instead of liquid fuel.. that is where I would start looking. As for the coolant temp sensor you can find a tempature to resistance chart on the net via a googlec search and check the sensor when it's been sitting out all night and comapir the resistance reading to what the air temp is and see if it's close.. Good luck :)

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