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1999 Ford F-150 Lean fuel mixture (bank 1 and bank 2)

Tiny
BOYCE1988
  • MEMBER
  • 1999 FORD F-150
  • 6 CYL
  • 2WD
  • MANUAL
  • 118,000 MILES
I've replaced these parts in the 30k miles i've owned the truck.
-camshaft sensor
-camshaft position synchronizer
-all new oxygen sensors
-new spark plugs and spark plug cables
-mass airflow sensor
-IAC control valve
-upper and lower intake manifold gaskets
-ABS sensor (rear only)
-alternator
.
I'm getting a lean fuel mixture reading and I'm running outta options to solve the problem.

Advice?
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Wednesday, April 8th, 2009 AT 12:07 AM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
A lean fuel condition can be caused by:

* 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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Wednesday, April 8th, 2009 AT 12:19 AM

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