I am trying to diagnose a problem with my truck.

Symptoms- sucks a lot of gas. It went from 15 mpg to 4 mpg
Error codes from actron ODBII cp9145-p1682(charging system voltage too low) and p0171 (bank 1) system too lean

I have changed all plugs,plug wires, and MAP sensor. I am guessing I have a rail plugged or injector plugged. I am not sure. All of the injectors OHM at 12 ohms.

Any thoughts?

 

probably an o2 sensor as its the one that actually senses the rich/lean mix. With your gas milleage i bet your running rich because the faulty o2 sensor is telling your computer that your lean regardless of mix. and whats the voltage of the electrical system while the engine idles?

 

I will check the sensors. They appear to send voltages withing spec (between 0 and 1 volt) and OHm out OK but they are probably cheap enough to replace. The exhaust has a lot of gas coming out of the system. When I accelerate, there is a lot of smoke from excess gas.

How do you check system voltage?

 

just check the voltage at the battery while the motor idles. it should be around 13-14v. i wouldn't drive your truck like that, your damaging your catalytic converter by overloading it with fuel. also i doubt you have anything wrong with your fuel delivery system and i highly suspect your o2 sensor. bottom line is that you know your running rich but the computer thinks its lean, thats your real problem

 

I wouldn't think the O2 could cause it to dump fuel like that. They only operate within a certain range. I would suspect that a fuel injector or two are stuck fully open.

 

i thought about that, but his computer is showing a lean code. if in fact an injector was stuck open wouldnt a properly working computer and o2 sensor read overly rich?

 

You would think so. It's hard to really diagnose this stuff without getting your hands on it.

I'd say there's probably more than one problem, because a lean code doesn't make sense when combined with really poor fuel economy.