Help with a 2008 silverado

[Andy H]

Hi everyone. I still have my 2008 silverado 5.3l. I have the intune that I used to disable AFM and changed the tire size back in 2015. Everything has been working great but I am now getting a check engine light. Was wondering if you all could help me out with it?

I recently had a check engine light come on after filling up my truck with gas. It is a 2008 Silverado with a 5.3l LY5 J code with 190,000 miles. The codes I am getting are P069e and P0606, (which have to do with the Fuel Pump Control Module and the PCM). My truck is running perfectly fine though, no problems at all. I started using my obd2 scanner to log data to help troubleshoot, because the codes would instantly come back as soon as I clear them. I was monitoring my fuel pressure and noticed it was running around 88 to 92 psi range according to my obd scanner.

I kept driving the truck since it was running great and would occasionally monitor the fuel pressure for any changes. I noticed that once my fuel tank got down towards 1/2 a tank, The fuel pressure dropped to around 42 psi. At this point, I was able to clear the codes and the check engine light would stay off. As I continued to drive the truck, the fuel pressure stayed around 42 and the check engine light stayed off. When the fuel level got down to around 1/8 of a tank, I stopped and filled up the fuel tank. As soon as I started the truck up while at the gas station, the check engine light came back on, and the fuel pressure went back up to around 92 psi. Truck still runs good though. Any ideas what would be causing this to happen? If it is the PCM, is there anything I could do to update it with my intune device?

Thanks!

[mikel]

its nothing related to the tune, as the tune cant change

Gotta be something related to the fuel level, but what exactly is causing it is unclear.