Shes running lean, P0171 P0174

[Eric3.0]

Hello, im new here and a fan of Rangers, of course. I own two right now, a 1998 and a 2000 2WD extended cabs.

My 1998 has the 3.0 and 256,000 miles and right now it is running lean in both banks, P0171 and P0174. I also have a code for the sensor switch maxed limit, because I think the computer is maxing out the long term fuel trim as much as it can to counter the lean condition.

I sprayed carb cleaner on a running engine to find vac leaks, checked every hose and vac source and checked fuel pressure. It acts like its running out of gas, I stop restart and it runs normal for a while again. The fuel pump seems loud so I decided to replace it, because with the symptoms and noise of it and the lean code, it seems like that is the problem. Probably has enough pressure to keep it running, but it loses pressure sometimes while driving and it acts like running out of gas. However when I check fuel pressure, it puts out 65PSI engine off and around 52-55 PSI engine on. It doesn't seem like a big drop to cause a problem. Im replacing the pump anyways, with the high mileage and the pump noise I decided it would be a good thing to do reguardless and it may just be the problem.

Another weird thing its doing now, is not feeding my pressure gauge any pressure hooked up to the fuel rail shrader valve. It like just stopped working yesterday, but it has to have pressure, because it starts quick and runs. The shrader isn't giving me a reading and there is a pressure regulator looking thing right next to the shrader and I wonder if that thing is the problem. Some have told me that is the fuel damper and my regulator is in the gas tank. I dunno.

I'm hoping the new fuel pump solves everything, but usually can't get that lucky.

If anyone has any ideas, tune in...I'll check it out.....I want to save my ranger, engine doesn't even burn oil, so I would like to get more miles out of it if possible...I take care of it otherwise, even if it's getting rusty and high miles.... Just has this damn pesky lean condition.

Eric.

 

[Dirtman]

Buy a Motorcraft pump, anything else will fail if it even works at all.

and yes the regulator is part of the fuel pump assembly in the tank, the gizmo on the rail is in fact a damper.

55psi is low to me (some say thats normal with engine on but my truck stays at 65psi running and my factory ford shop manual says it should stay above 62psi)

I would also change the fuel filter before changing the pump if you haven't done so recently.

 

[Sharky]

try the fuel filter 1st if it hasnt been changed for a while.

 

[RonD]

Welcome to TRS

How old are the O2 sensors?
These are the only sensors that wear out, they use a chemical to detect Oxygen in the exhaust and they run out of that chemical
100k miles or 12 years which ever comes first
And they go LEAN as they run out of chemicals
So if you have noticed lower MPG lately then you are getting FALSE Lean from old O2s

To have both banks go lean at the same time is a long shot for old O2s, but not a no shot, lol