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1991 GMC Sonoma LEAN FUEL MIXTURE

Tiny
JRBOOBEAR29
  • MEMBER
  • 1991 GMC SONOMA
  • 4 CYL
  • 2WD
  • MANUAL
  • 130,000 MILES
My truck is hard to start. After three tries, it will start. I can drive it about 5 miles, then the check engine light comes on for lean mixture. It will act like it's not getting gas and bogs. I pump the accelerator 5 or 6 times, and it's good for a few miles and keeps repeating this. Also, when it is driving ok, if I punch the accelerator to go, it hesitates a little but then picks up a little, but not like it should.
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Friday, June 26th, 2009 AT 2:07 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
1991 GMC Sonoma LEAN FUEL MIXTURE

A lean fuel condition can be caused by the following

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
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Saturday, June 27th, 2009 AT 6:08 AM

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