I drive a 91 GTA with a 305 TPI with 4 speed auto. When my car sits for awhile and I start it up, a puff of black smoke comes out of the exhaust pipes. From reading GM Service Brochures and this message board, it is due to an overly rich fuel mixture. I would appreciate it if anyone could tell me what the cause(s) of this is. Thanks.

 

It could be a leaking injector, I guess. Are you sure it is not a bluish oil burning smoke, which would be the valve seals and posibly worn valve guides.

 

Thanks for your input. I'm positive that it is black smoke. My mechanic said that a fuel injector pressure test could be done to see if any were leaking. I just wanted to see if anyone else had an idea about what could cause this.

 

You could have a bad coolant temperature sensor. This will tell the computer that you're like -500 degrees and it will rich the crap out of the car when it starts. My firebird riched out so bad that it would flood and not start.

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Andy, if it's black smoke only in the morning when you first start your car, it is most probably a leaking injector(s). Does it run rich any other time besides extended starting intervals?

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To my knowledge, there is only black smoke when I start the car up, occasionally, its not bad, but I want to get it fixed. I will probably get a fuel injector pressure test next week to see if that is the problem. Thanks for the posts. If anyone thinks it could be anything else let me know.

 

If it doesn't smoke when you get on it, or after quick stops, I would say the problem is with a leaking injector(s).