1990 Buick Lesabre

Tiny
RACERTC
  • MEMBER
  • 1990 BUICK LESABRE
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 157,000 MILES
I've had this car for 4 years and it just now has started to act up. It is pushing out black smoke, has a missfire in cylinder 3, 5, and 6. It has been doing this off and on for 2 weeks now and getting progressivly worse. Ecm has been changed and the coil pac too, reacently did a fuel pressure check and it is fine running normal but slightly low (guessing because of ths problem). I was told it could be the cat convt. But now with the black smoke I have no idea.
Monday, July 25th, 2011 AT 2:17 AM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Black smoke indicates a rich fuel mixture

Probable causes of an engine running rich are as follows:

1. Excessive fuel pressure can be cause by restricted fuel return line
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.
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Thursday, October 13th, 2011 AT 3:45 AM

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