Never ending P0171 error

[Jeff352]

I have a 2000 XLT V6 SOHC with 171K. I had my CEL come on almost a year ago and the OBD code showed P0171 and P0174. The engine runs great, no hesitation, no rough idling. I have some timing chain chatter when the engine is cold, but it goes away once the engine runs for a couple of minutes. Over the past month and after reading the posts here, I have tried to fix the issue with the CEL and had only partial success. The P0174 code no longer comes up. I have checked the fuel pressure at the Schraeder valve and it is 44. I replace all four O2 sensors, new spark plugs and wires, replaced intake gaskets, no vacuum leaks-followed every line and no cracks or noises-even sprayed carb cleaner everywhere and no RPM changes, replaced EGR pressure sensor. Cleaned MAF sensor. Where do I go from here to resolve this?

 

[2000StreetRod]

low fuel pressure

Your 2000 fuel system is the non returnable type. The fuel pressure should be above 60 psi for all engine conditions. See Fuel pressure test procedure
If it has been more than 30,000 miles since the fuel filter has been replaced I suggest you install a new one. I suspect that clogged fuel filters cause early fuel pump failure. See Why change fuel filter?

 

[Jeff352]

Buy the pump or the whole sending unit

Your 2000 fuel system is the non returnable type. The fuel pressure should be above 60 psi for all engine conditions. See Fuel pressure test procedure
If it has been more than 30,000 miles since the fuel filter has been replaced I suggest you install a new one. I suspect that clogged fuel filters cause early fuel pump failure. See Why change fuel filter?

Can I buy just the pump ($80) or do I need to replace the whole sending unit ($230)?

 

[2000StreetRod]

pump & sock

I would buy just the pump and "sock" (screen filter) if the fuel gauge is working correctly. However, first I would replace the fuel filter to make sure it is not restricting fuel flow.

 

[Jeff352]

2000streetrod was right. Replaced fuel pump and P071 CEL is now off. Thanks so much for the help