2007 Chevrolet Tahoe Z71, miss firing

2007 CHEVROLET TAHOE
97,997 MILES • V8 • 4WD • AUTOMATIC
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MAEDAY77
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Hello, I purchased a used 2007 Tahoe Z71 and it's been miss firing (missing) 2 wks after my purchase. The check engine came on so I had it serviced: new axles, fuel system cleaning and another week later they had to replace the fuel pump. The techs say my spark plugs are good, but after all this my tahoe still misses while stopped. It does have 97k miles, use to be a fleet. Any idea? Thank you in advance.
Aug 19, 2011 at 3:33 PM
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WRENCHTECH
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What are the exact code numbers being set when the check engine light comes on?
Aug 19, 2011 at 4:44 PM
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MAEDAY77
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P0171 and P0172. Prior to replacing the fuel tank it was putting out 48PSI. That has been corrected, but it's still missing. There is no chk engine light on currently.
Aug 19, 2011 at 9:00 PM
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WRENCHTECH
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I think you meant PO171 and PO174.
What is the fuel pressure now?
Aug 19, 2011 at 11:11 PM
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MAEDAY77
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Yes, PO. It's now at 65PSI now.
Aug 20, 2011 at 1:38 AM
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WRENCHTECH
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You should be getting some misfire codes if it's still missing.
Aug 20, 2011 at 1:42 AM
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MAEDAY77
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That's what's baffling, it is not giving us any other codes. Well thanks for trying.
Aug 20, 2011 at 3:47 AM