OBD II code help.

[rlsc98]

I need some help with this code, it popped up today on my 97 305.
the code # is PO171 (bank 1 too lean) could this be pointing to 1 of the 4 O2 sensors on this engine?
thanks in advance.

[MT-2500]

A code does not say replace the02 sensor. It says check it out.
In your case the code is for bank 1 running lean.
First thing I would check fuel pressure up to specs.
Here is a pdf link for checking code 171.
Let us know what you find.
http://members.troublecodes.net/crunch/171.pdf
Also on fuel pressure checking.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.
MT

[rlsc98]

Well i hooked up my pressure gauge readings are as follows
cold start 2 psi for 2 secs.
after 2 secs dropped to 54 psi @ idle
57 psi @60 mph
60 psi accelerating
63 psi @ hard accel.
When I pulled in the driveway and stopped it maintained 54psi and when i turned it off i counted to 9 and it had dropped to 40 psi. , 20 min later it dropped to 20psi and after a couple of hours no pressure. A week ago i replaced the fpr,sprk. plugs,cap,rotor. and the fuel pump is about 2 yrs old,GM dealer installed.
Truck has 120000 miles on it, and aside from the fpr and fuel pump the truck hasnt been worked on.
thanks in advance.

[MT-2500]

your pressure is low. Make sure your gauge is accurate.
Also run a full fuel pressure test on the pump.
First pinch off return line at rubber part and check pressure. Then make a direct connection at fue filter and check.
If your pump is good it will put out 75-85 or more lbs of pressure.
If the pump is good check the fuel pressure reg.
MT