This is getting insanely frustrating.
2008 Yuke with 6.2L. Replaced rotted out leaking fuel pump, now I have unending p0171 and p069e codes that only occur on a cold start-up or if the motor is off while hot for more than 15 minutes. The codes pop up exactly 30 seconds after startup (a provisional code for both and an actual code that lights the CEL).
Here is what has been done:
Four independent diagnostic processed by four independent mechanics and two diagnostic attempts by two stealerships - every one insisted a new fuel pump was needed and I have now been through four new OEM GM pumps and the error codes keep popping up:
Fuel pressure on the rail is where it should be as is the fuel pressure from the pump. All live data, etc., is perfect.
No issues with the wiring harnesses, voltages and signals.
Each component (fuel pump, FPCM, ECM, Fuel Rail Sensor and anything else related you can possibly imagine) check out OK. Yes, we even tried a new FPCM and reflashed the ECM even after each component checked out as working perfectly fine.
There are no performance issues with the vehicle at all but these codes keep getting set. The vehicle has been driven at least 1000 miles (as each of the mechanics/techs suggested) to see if the problem goes away. It does not. Erase the error codes and they come back on the next cold start after exactly 30 seconds twice, or after you let a hot engine sit for more than 15 minutes exactly (and then 30 seconds after a start, here comes the codes again.
The only thing I can think of is that the fuel pressure sensor has a temperature related fault that only occurs under two specific conditions. The GM service manuals are silent on all possible causes beyond what the manuals say are possible.
I find it statistically hard to believe that the fuel rail pressure sensor should coincidentally fail just exactly at the same time the fuel pump is replaced. And, I know if I waste my time replacing the Fuel Rail Pressure Sensor, the issue will not be fixed knowing my luck.
One mechanic suggested that it could be because the gas distributors are boosting the ethanol content to 15% (the last batch of fuel I bought I tested as having upwards of 20% to 25% ethanol. No kidding) and that excessive ethanol can F up the pressure sensor or otherwise trick the sensor into thinking the fuel pressure is off (ethanol compresses in liquid form than gasoline and excessive ethanol gasoline will compress at an even higher ratio - I simple vapor pressure fluid mechanics equation and lead to a faulty data signal on a worn, old sensor). Either way, the engine temperature and time the motor is off while hot seems to be related to this issue. Once the motor is up to temperature and the code is erased, the problem subsides until the next cold start or start after sitting for 15 minutes.
One question is involving the P0191 code which is only described as a "performance range issue" involving the Fuel Rail Pressure Sensor. Does this imply a fuel pressure issue or an issue with the sensor itself before the motor even starts? The 'provisional' codes appear to be set between turning on the ignition switch and actually cranking the motor. Again, if I erase the codes while the motor is running after the CEL illuminates, the issue doesn't occur thereafter until the next cold start or the motor is off for more than 15 minutes while warm.
What am I and all the mechanics missing here? I have a feeling it's something obvious that no one can think of. Do I potentially waste my time running down this problem or do I just sell it to the next unsuspecting slob with full disclosure just to recover the $3000 I have already dumped into fixing this unsolvable problem? Or should I just ignore the error codes and keep driving it until it takes a dirt nap or drive it down to West Memphis, pull the plates, leave the keys, hang a sign on it that says "steal me" and collect the insurance? (That last one is a joke... maybe, LOL!).
But seriously, what is everyone missing with this issue?
2008 Yuke with 6.2L. Replaced rotted out leaking fuel pump, now I have unending p0171 and p069e codes that only occur on a cold start-up or if the motor is off while hot for more than 15 minutes. The codes pop up exactly 30 seconds after startup (a provisional code for both and an actual code that lights the CEL).
Here is what has been done:
Four independent diagnostic processed by four independent mechanics and two diagnostic attempts by two stealerships - every one insisted a new fuel pump was needed and I have now been through four new OEM GM pumps and the error codes keep popping up:
Fuel pressure on the rail is where it should be as is the fuel pressure from the pump. All live data, etc., is perfect.
No issues with the wiring harnesses, voltages and signals.
Each component (fuel pump, FPCM, ECM, Fuel Rail Sensor and anything else related you can possibly imagine) check out OK. Yes, we even tried a new FPCM and reflashed the ECM even after each component checked out as working perfectly fine.
There are no performance issues with the vehicle at all but these codes keep getting set. The vehicle has been driven at least 1000 miles (as each of the mechanics/techs suggested) to see if the problem goes away. It does not. Erase the error codes and they come back on the next cold start after exactly 30 seconds twice, or after you let a hot engine sit for more than 15 minutes exactly (and then 30 seconds after a start, here comes the codes again.
The only thing I can think of is that the fuel pressure sensor has a temperature related fault that only occurs under two specific conditions. The GM service manuals are silent on all possible causes beyond what the manuals say are possible.
I find it statistically hard to believe that the fuel rail pressure sensor should coincidentally fail just exactly at the same time the fuel pump is replaced. And, I know if I waste my time replacing the Fuel Rail Pressure Sensor, the issue will not be fixed knowing my luck.
One mechanic suggested that it could be because the gas distributors are boosting the ethanol content to 15% (the last batch of fuel I bought I tested as having upwards of 20% to 25% ethanol. No kidding) and that excessive ethanol can F up the pressure sensor or otherwise trick the sensor into thinking the fuel pressure is off (ethanol compresses in liquid form than gasoline and excessive ethanol gasoline will compress at an even higher ratio - I simple vapor pressure fluid mechanics equation and lead to a faulty data signal on a worn, old sensor). Either way, the engine temperature and time the motor is off while hot seems to be related to this issue. Once the motor is up to temperature and the code is erased, the problem subsides until the next cold start or start after sitting for 15 minutes.
One question is involving the P0191 code which is only described as a "performance range issue" involving the Fuel Rail Pressure Sensor. Does this imply a fuel pressure issue or an issue with the sensor itself before the motor even starts? The 'provisional' codes appear to be set between turning on the ignition switch and actually cranking the motor. Again, if I erase the codes while the motor is running after the CEL illuminates, the issue doesn't occur thereafter until the next cold start or the motor is off for more than 15 minutes while warm.
What am I and all the mechanics missing here? I have a feeling it's something obvious that no one can think of. Do I potentially waste my time running down this problem or do I just sell it to the next unsuspecting slob with full disclosure just to recover the $3000 I have already dumped into fixing this unsolvable problem? Or should I just ignore the error codes and keep driving it until it takes a dirt nap or drive it down to West Memphis, pull the plates, leave the keys, hang a sign on it that says "steal me" and collect the insurance? (That last one is a joke... maybe, LOL!).
But seriously, what is everyone missing with this issue?
