2008 Yukon Denali - New Fuel Pump issues (P069E and P0191 codes)

[Gildan]

Installed new OEM fuel pump and I am now getting the P069E and P0191 fault codes.

Occurrence: These coded light up the CEL about 2 minutes after a cold start. If I clear the code after the engine reaches operating temperatures, the codes do not appear until the next cold start. Checked the live data and hidden/permanent codes, nothing there. Live date from a test drive shows no issues at all. Reference voltages and circuits check out to exact specs. I managed to get a local dealership to do a diagnosis for free (It helps to know the right people) and they found absolutely no reason for these codes to be popping up. However, we did discover that the technical diagrams did not resemble what was there in this vehicle.

Individual components appear to be working properly when we test them. The fuel pump control module checks out OK, the pump and associated lines are new, the electrical connections and lines show no issues.

The question is what is causing this. The only component I can think of is the fuel pressure sensor which I think is attached is experiencing an intermittent mechanical issue, or the fuel pressure regulator is experiencing an intermittent mechanical failure. The fuel pressure is correct when you check it with a mechanical gauge. Has anyone experienced this particular issue after installing a new fuel pump, and if so, is there a solution to this issue?

 

[SpareParts]

Always a chance of a faulty new pump.
I would look hard at the FPCM.

 

[Fless]

Diagnostic paths:

P069E — 2008 GMC Yukon Denali AWD V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon Denali AWD V8-6.2L.

charm.li

P0191 — 2008 GMC Yukon Denali AWD V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon Denali AWD V8-6.2L.

charm.li

 

[Gildan]

Always a chance of a faulty new pump.
I would look hard at the FPCM.

That is a distinct possibility. I went through three brand new OEM GM pumps and the 4th one is racking up the same codes. The dealership checked the FPCM and the pressure on the fuel rail, etc., and said the FPCM was good. So, for a number of reasons, I think the fuel pressure sensor is intermittently sticking which is the last logical possibility - meaning that there is lacquer in the sensor that hardens up when the engine cools down and frees up when the vehicle is at operating temperature, or; the pressure sensor coincidentally shit the bed.

 

[Gildan]

Diagnostic paths:

P069E — 2008 GMC Yukon Denali AWD V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon Denali AWD V8-6.2L.

charm.li

P0191 — 2008 GMC Yukon Denali AWD V8-6.2L Service Manual | Operation CHARM

Detailed repair manual for the 2008 GMC Yukon Denali AWD V8-6.2L.

charm.li

That's the documentation I was also provided by the GMC Service department at the dealership. So, I decided to do a little test just to see if the pressure sensor was functioning properly.

I rigged up a proper power supply and used my multi tester to see how the pressure sensor was behaving. To make a long story short, it seems that when the sensor is cold, the mechanical element of the sensor is sticking or behaving sluggishly. Apply a little heat to it, and it functions normally for a while and then intermittently malfunctions at random intervals. The vehicle has about 240K miles on it and a part like the fuel rail pressure sensor is probably living on borrowed time after 18 years and that many miles. It's the cheapest part to replace and if worse comes to worse, I can get a pre-programmed FPCM for about $200. All the wiring/circuits test OK without any issues as do all the voltages and resistance, etc.

A bad fuel pressure sensor will cause the FPCM to call for data and set a P069E code and CEL. Now, the whacky issue is how to bleed down the residual pressure on the fuel like properly. This Yuke has no solenoid in the fuse block to pull. If I pull the fuse for the fuel pump, the engine runs just fine without sucking out the fuel in the line and stalling out. Go figure.

 

[Fless]

See duplicate thread:

2008 Yukon Denali - Ongoing Saga of the Unrepairable/Undiagonsable P0171 and P069E Error Codes

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...

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