engine idle eratic when started cold

2000 FORD EXPEDITION
90,000 MILES
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TSNAKE
  • MEMBER
  • 2 POSTS
no codes, runs great after warmed up
Dec 30, 2011 at 9:20 PM
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RIVERMIKERAT
  • ✓Experienced Mechanic
  • 6,106 POSTS
Check fuel pressure and for vacuum leaks.
Dec 30, 2011 at 9:39 PM
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TSNAKE
  • MEMBER
  • 2 POSTS
Thanks will check further but didn't find any leaks before and would think that the fuel pressure would tend to be lower when hot if the pump was starting to fail.
Dec 30, 2011 at 10:00 PM
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RIVERMIKERAT
  • ✓Experienced Mechanic
  • 6,106 POSTS
Resistance in wires is higher when cold and lower when hot. If the internal resistance of the pump has increased, the cold wires can make it worse.
Dec 30, 2011 at 11:42 PM
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