I have a 1997 Ford Ranger 4cyl 2.3L motor. It has about 104,000 mi on it and it has been maintained quite well since I've had it (bought it when it had 80k).

Recently it broke down on the high way. It sputtered in idle and would stop, when I would get running to move forward it would only do so for a short period of time and then die. I ran an OBD II on it from the Autozone across the street and 2 codes came up P0171 and I forget what the other one was (should have written it down I know). I changed the fuel filter out thinking it might be a fuel problem but it did not work. I had the vehicle towed to a shop where they replace the MAF sensor. The shop tested the vehicle with the new MAF sensor and the MAF shorted out. They then put a new computer in the truck (new one with the correct software from the ford website) and an additional MAF sensor.

As soon as I drove it out of the shop the check engine light came on again. I took it back and the code P0171 showed up again (and was the only code). He said it might be due to the very cold weather (Chicago area). He said to bring it back if it still has problems.

I've already spent $650 getting it fixed.

The truck ran fine for about 150 miles and now it is doing the same thing again. The mechanic checked the truck and said the fuel pressure was right. What could this possibly be?

Well, from what i'm seeing with googling the code, this is your problem
Technical Description

System Too Lean (Bank 1)
This means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust).

These may be your causes
A code P0171 may mean that one or more of the following has happened:

* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak downstream of the MAF sensor.

And then some possible solutions
* In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
* Inspect all vacuum and PCV hoses, replace if necessary
* Check for a dirty fuel filter and proper fuel pressure


Thanks to google for all the info.

__________________
2000 2.5L Ford Banger

What I've Done: Pioneer Head Unit, Nexen 31" Tires, Projector Headlights, Manual To Power Locks, Jet Black Paint Job, American Racing Baja Rims, Billet Grille, Herculiner, Rail Caps, Tinted Windows, Explorer Radio Bezel, Wired Bezel For Projectors, Kicker Sub/ Visonik Amp, Black Carpeting, Kicker 6x9 Speakers, High-Flow Air Intake, New Horn, Black Interior. Center Console, many more still in process.

How do you check the fuel pressure? I too have the same issue. Check engine light has been on for 8 years, truck runs fine though. I have done all the "symptoms" that are suggested, BUT I don't have any pressure release when I unscrew my gas cap. I changed the cap, and that isn't the issue. Any thoughts?

Hi,

Most vehicles have a Schrader valve (like a tire) you can use to check for fuel pressure using a pressure gauge. Often times you will find this valve on the fuel rail.

hope that helps!
Wily

Hey, thanks. Can you tell me what it looks like? Will that fix my fuel tank pressure and maybe my P0171 code?

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Ok, I just googled the valve. I understand what it looks like now, but I still ask the second part. This check engine light is killing me in frustration for the past 8 years.

Thanks

lol. glad you found it. pretty easy to identify aye?
the valve won't fix anything. it's basically a diagnostic port. the P0171 sounds like it is a sensor reporting a lean mixture. As mentioned above that means there is too much oxygen in your exhaust basically (or as far as i interpret it). So you have either too little fuel or too much air.

Too little fuel could potentially be due to low fuel pressure, seems possible, anyone else want to chime in on this? Could also be a fuel filter being clogged or an injector or something along those lines.

Too much air could be an intake leak somewhere. I've heard of scenarios where a leaking intake manifold gasket allows more air into the combustion chamber and causes a lean scenario.

In the spirit of complete transparency I do want to let you know that I am still learning daily about automotive repair. One of the more seasoned forum members may have another idea or may contradict what i say. We are all here to learn so if there is something else I missed or anything I look forward to the correction!

Hope some of this helps. If you have a gauge you can test your fuel pressure and see where it's at. thats a good start at least. If you dont have one you can usually get them fairly inexpensively.

Cheerz!
Wily

Hey, thanks. Your info is all good and matches what I have also learned over time. I have too symptoms that I need to fix first. One is an unseated oil dipstick and the other is no pressure in my fuel tank, i.e. no releasing pressure hissss unscrewing the cap. Could those be my culprits? I just don't know.