engine runabilty

130,000 MILES • V8 • 4WD • AUTOMATIC
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GEOINAK
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1993 chevy k1500 with 5.7 runs rough, blows excessive black smoke, poor fuel economy, no codes present? Have replaced MAP sensor.
Dec 4, 2010 at 12:13 PM
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BMRFIXIT
  • ✓Experienced Mechanic
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Black smoke running rich to much fuel \check fuel pressure regulator
O2 sensors
coolant sensor
Dec 4, 2010 at 12:17 PM
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LEGITIMATE007
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ok it sounds like you have a leaking or several leaking injectors.also you may want to check the fuel pressure regulator,you may be pushing more fuel/(running rich) because of this
Dec 4, 2010 at 12:18 PM
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LEGITIMATE007
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BMRFIXIT, makes a good point, you may not be going into closed loop, which means a bad oxygen sensor or even engine coolant temp sensor.
Dec 4, 2010 at 12:19 PM
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GEOINAK
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Thank you for the quick responses. Shouldn't i be getting check engine light and codes with bad o2 sensor and/or coolant temp sensor?
Dec 4, 2010 at 12:43 PM
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BMRFIXIT
  • ✓Experienced Mechanic
  • 19,053 POSTS
Not always and you can not depend on the check engine light
you can scan data for reading
Dec 4, 2010 at 12:57 PM
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