1992 Chevrolet Corvette Black Smoke

CHEVROLET
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DRUEFLE
  • MEMBER
  • 8 POSTS
I have a 1992 chevrolet corvette with 168,000 miles. If the car is cold it is hard to start will continually turn over but will only start if given gas, but if I drive it a while and cut it off it will crank right up. I've also noticed that when I drive it to work in the morning which is only about 5 miles from home when I go to crank it up at lunch a little bit of black smoke comes out of the exhaust, but thats the only time I see the black smoke is at this time of the day, everyday. There is also a strong smell of gasoline coming from the exhaust at all times. I've also noticed white smoke coming from the exhaust when engine is cold, but it goes away after the engine has heated up. Its been put on a diagnostic machine and the MAP sensor was bad so that was replaced.
Jan 5, 2007 at 1:51 PM
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BURRBRIAN
  • ✓Experienced Mechanic
  • 158 POSTS
Hi, it sounds like you're running a little rich on the gas side. Mostly black smoke= gas, blue smoke= oil, and white smoke= water- moisture. Seeing as you make short trips the white smoke is condensation burning out and having replaced MAP sensor maybe you should have had your fuel mixture adjusted. I think it should be fuel injected so you shouldn't have to be hitting the gas to get it to start Sounds to me like you just need a little fine tuning to get back to running right. :lol:
Jan 6, 2007 at 3:16 AM
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DRUEFLE
  • MEMBER
  • 8 POSTS
Thank you for the help.
Jan 6, 2007 at 7:02 AM
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Suggested Repair

The engine appears to be running rich. Have the fuel mixture checked and the fuel-injection system fine-tuned so it starts without throttle. White smoke on short cold trips is likely condensation, not a coolant leak.

Conversation Summary

A 1992 Chevrolet Corvette with 168,000 miles is hard to start when cold unless given throttle, but starts normally when warm. After a short morning drive, a little black smoke appears at the next start, and the exhaust always smells strongly of gasoline. White smoke when cold disappears once the engine warms. A bad MAP sensor was already replaced. The expert said black smoke indicates a rich fuel mixture, white smoke on short trips is moisture, and the fuel mixture should be adjusted and the fuel injection fine-tuned.

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