P0171 Code 97 Grand Caravan 3.3

I have a 97 Grand Caravan with a 3.3 litre engine, it has 123,500 miles. The other day on the way to an amusement park, after driving about an hour at highway speed with the AC running on high. When I got off an exit ramp I found myself in stop and go traffic due to a detour/delay, I noticed the check engine light came on. It seemed to run a little rough, I suspected a dirty injector or maybe a sparkplug mis-fire. It seemed to smooth out as I drove it another 45 minutes or so. There were a couple of times (in the stop and go traffic) where it seemd like it didn't accelerate..I'd press the acceleator and instead of speeding up..it would almost act like the transmission wasn't shifting to a lower gear. The van sat for 12 hours or so while we were in the park. It resarted just fine...I sopped at Wal-Mart and put some Trechtron fuel Injector cleaner in the tank and then drove 150 miles or so home; the check engine light turned off on the way. I checked the code when I got home it was P0171. My generic code book says the = Lean Fuel Mix Bank 1. I read a posting here that stated this indicated a bad fuel pump Does anyone else have experience with this P0171 code? Does it indicated it low pressure or is there a problem with the fuel mix i.e. fuel injection/ computer & sensors controling the mix. I can put a fuel pump In if that's what it really needs. What steps would you take to confirm it is a bad fuel pump?. I would love to hear fom any and all that has had a P0171 and what you did to fix it and how you confirm a failing fuel pump

Thanks Spit

This may explain where to look:OBDII Error Summary related to Fuel Mixture
Code Detected Condition Trouble Area
P0171 System too Lean (Bank 1)

When air fuel ratio feedback is stable after engine warm up, fuel trim is considerably in error on the RICH side (2 trip detection logic) Air Induction System Leak
Injector Blockage
Mass Air Flow Meter
Engine Coolant Temperature Sensor
Fuel Pressure
Gas Leakage from the Exhaust System
Open or Short in the Oxygen Sensor or associated wiring
Oxygen Sensor Defective
Engine Control Unit

P0172 System too Rich (Bank 1)

When air fuel ratio feedback is stable after engine warm up, fuel trim is considerably in error on the LEAN side (2 trip detection logic) Injector Leak, Blockage
Mass Air Flow Meter
Engine Coolant Temperature Sensor
Ignition System
Fuel Pressure
Gas Leakage from the Exhaust System
Open or Short in the Oxygen Sensor or associated wiring
Oxygen Sensor Defective
Engine Control Unit

Check for a vacuum leak first then clean the MAF sensor with electronics cleaner, be gentle. The other causes are listed above and should be fairly straight forward to try. I hope this helps

Thanks for the input. It was a bad fuel pump. The spec on the fuel pressure is 49 psi. When I first started the van it would have 40-50 PSI then ithe needle would start to oscillate like mad and begin to fall down to the low to mid 20's. Once while I was watching it below 20 and the engine began to miss. I replaced the complete pump assby including the pressure regulator. I also installed a new fuel filter asby. Which I don't believe was ever changed. Now that I have been underneath it and seen the fuel filter..I really think that the fuel filter could be changed without completely dropping the tank...and I wish I had done it 60k miles ago.

I bought a fuel pressure meter for $35. Advance Auto doesn't have those to lend, and they said no other Parts stores would either, it's a slick gadget. It made the diagnosis so much easier. I think sometimes we ask everyone in this forum to read a code or guess at a cause and give us a fix. That can make for a lot of guessing and wasted $$ on parts that don't do the job that could have paid for the test equipment.
I would encourage everyone to consider investing in tools/test equipment. For some things like OBD II codes, electical readings, fuel pressure etc. test equipment it's really the only way to go.

By the way dropping the tank and all isn't to god-awful bad. It would have been a lot easier if I had been able to get more gasoline out of the tank..Does anyone have a recommendation on a siphon/procedure for this? But back to my point about test equipment...I would have been pissed to get this done and have been wrong about the diagnosis.

I used a big 4-5 inch C-clamp to un-screw the cap that holds the pump on I just tightened it down around the cap in between the ridges and it worked great. The same type of big C-Clamp used to push calipers back I bet most members of this forum have one.

Thanks Again for the replies..this forum & it's members are the greatest!!!

Spit




QUOTE=GTP Dad]This may explain where to look:OBDII Error Summary related to Fuel Mixture
Code Detected Condition Trouble Area
P0171 System too Lean (Bank 1)

When air fuel ratio feedback is stable after engine warm up, fuel trim is considerably in error on the RICH side (2 trip detection logic) Air Induction System Leak
Injector Blockage
Mass Air Flow Meter
Engine Coolant Temperature Sensor
Fuel Pressure
Gas Leakage from the Exhaust System
Open or Short in the Oxygen Sensor or associated wiring
Oxygen Sensor Defective
Engine Control Unit

P0172 System too Rich (Bank 1)

When air fuel ratio feedback is stable after engine warm up, fuel trim is considerably in error on the LEAN side (2 trip detection logic) Injector Leak, Blockage
Mass Air Flow Meter
Engine Coolant Temperature Sensor
Ignition System
Fuel Pressure
Gas Leakage from the Exhaust System
Open or Short in the Oxygen Sensor or associated wiring
Oxygen Sensor Defective
Engine Control Unit

Check for a vacuum leak first then clean the MAF sensor with electronics cleaner, be gentle. The other causes are listed above and should be fairly straight forward to try. I hope this helps[/QUOTE]