Ok now some new news.
Fired it up again today and she seems to run fine. Better than before but then my "check engine" light came on. So I thought, hmmm, no check engine light before and no codes and truck wouldn't run. Now truck runs fine but has check engine light. I bet there are codes. Break out the OBD 2 tester and sure enough there are 4 codes.
Please help me decipher where the problems lie and how to effect the repairs.
(generic DTC code) po171-system too lean bank 1
(generic DTC code) po174-system too lean bank 2
(Ford DTC Code ) po1151-lack of upstream heated oxygen sensor-sensor indicates lean bank 2
( Ford DTC Code) po1131-lack of heated oxygen -sensor indicates lean

So the original problem was a bad FPR.. With that changed and the truck running what do these codes mean and where are these sensor switch's?
Bummer. I need help again..

 

I sent the message in error

 

Also one note after you all chime in and help with this, how do I reset the computer to get the check engine light off?

 

If you start a key on engine off test, pull the jumper wire when the codes start blinking. That will clear the codes. If you want to completely reset the computer, both codes and adaptive strategies, disconnect the battery for 10 minutes or so.

 

Thanks. I will try these when I fix the problem.
No one yet has suggested where to start to understand this "lean" problem.
I am thinking it is in the sensors on the air intake??
Oxygen sensor??

 

I told you wrong earlier. You have OBD-II, so disregard what I said about pulling the jumper wire. I'd disconnect the battery for a while. I've heard folks suggest to turn on the headlights or something to drain the capacitors in the computer, but I really don't know if that works or if it is necessary.

 

Ahhh so gwashoppa. Thanks for the correction..
Wish someone would jump in on what my codes mean and what needs to be repaired/replaced??

 

Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174 bank (2) indicate the fuel/air ratio is too lean. The fuel adaptive system is at the rich correction limit.

Possible causes:

Fuel system
-- Low fuel pressure.
-- Contaminated injector(s)

Induction system
-- Bad or contaminated MAF sensor.
-- Air leaks after the MAF.
-- Vacuum leaks.
-- PCV system.
-- Fuel purge system.
-- Improperly seated dip stick.

EGR
-- Leaking gasket.
-- Stuck open EGR valve.
-- Leaking diaphragm.

Base engine
-- Oil overfill.
-- Cam timing.
-- Cylinder compression.
-- Exhaust leaks before or near the HO2S's.

Check air intake for leaks, obstructions and damage.
Verify integrity of the PCV system.
Check for vacuum leaks.

Diagnostic Trouble Codes (DTCs) P1131 bank (1) (Cylinder #1) and P1151 bank (2) indicate the fuel/air ratio is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt.

Possible causes:

Fuel system
-- Low fuel pressure.
-- Contaminated injector(s)

Induction system
-- Air leaks after the MAF.
-- Vacuum leaks.
-- PCV system.
-- Fuel purge system.
-- Improperly seated dip stick.

EGR
-- Leaking gasket.
-- Stuck open EGR valve.
-- Leaking diaphragm.

Base engine
-- Oil overfill.
-- Cam timing.
-- Cylinder compression.
-- Exhaust leaks before or near the HO2Ss.

Check air intake for leaks, obstructions and damage.
Check air filter, air filter housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.

 

Above is what the book says.

I think I would put a gauge on that fuel manifold and see what the fuel pressure is with it running, should be about 33 to 36 PSI at idle.
Then take the vacuum hose off the FPR, plug it, run the engine and see what the fuel pressure is now, it should be 45 PSI.

 

Thanks Bill. Great info.
I'll get started. I may have left something unplugged or off. I'll check all that first and then round up a pressure guage. Do you check it at the valve stem fitting on the top of the fuel rail?

 

Yes, that is where you check it.

 

So how did it go? I've got the same problem. The codes thrown while running are 412 - Cannot control RPM during KOER high rpm check, followed by 311 - Thermactor air system fault during engine run self-test, 538 - Invalid cylinder balance test due to throttle movement during test. I'm thinking fuel filter (not likely but might as well), IAC valve (easy to R&R), followed by throttle position sensor R&R (remove throttle body, clean, replace TPS, re-install)

 

My problem after I replaced the IAC and Fuel pressure regulator was a clogged area at the MAF sensor. Been running good ever since. I also changed the fuel filter that had not been done just in case.
Now I did have a recent "check engine light" and when I checked it out with the OBD II sensor, it was an exhaust gas recirculation imbalance. I think code 411. Well, it has been so hot here and I checked several other things that I thought maybe it was a "ghost" trip of the on board computer. So I cleared the computer and so far, the check engine light is out and not a problem.
I do have 152K on the odometer now. But the old Ford is still going strong.
This is a great place to come for help and there are many knowledgeable people here that are willing to help..