1994 Ford F350 rich fuel and hard shifting

1994 FORD F-350
175,000 MILES • V8 • 2WD • AUTOMATIC
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STEVEM1
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  • 1 POST
the engine is 7.5 liter 460, it runs fine sometimes and shifts fine and then all of the sudden it starts running real rich and starts shifting really hard. We have replaced the egr valve and a few other sensors, spark plugs, wires and coil.
Aug 13, 2010 at 11:08 AM
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RASMATAZ
  • ✓ASE Certified Mechanic
  • 75,992 POSTS
  • ASE Certified Mechanic
Probable causes of an engine running rich are as follows:

1.Fuel pressure not within specs.Can be cause by restricted fuel return line or defective fuel pressure regulator.
2.Defective Oxygen Sensors.
3.Leaking injectors.
4.Coolant temperature sensor out of calibration.
5.Restricted air intake system.
Aug 14, 2010 at 6:07 AM
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