Low fuel pressure on 2012 Silverado. P171 and P174 codes lean left and lean right bank. Dealership told me the fuel pump was bad. I replaced and it had no effect Truck runs good, mileage is single digits. I felt like it might not be the pump but a regulator (didn't know my truck didn't have one at the time). I found out that it didn't have one so that was why I went ahead and replaced the pump.
JA: Has your car been stalling?
Customer: The weird thing about it is static pressure will be at least 65psi. When started, it will maintain a steady 55psi for approximately 7 seconds with the engine
warm. Then it will drop to about 41psi and stay there.
JA: What is the make/model of your car?
Customer: No 2012 Chevy Silverado 5.3 Vin 7
JA: Are you fixing your Silverado yourself? What have you tried so far?
Customer: Checked fuel pressure, checked for vacuum leaks, and replace my fuel pump assembly.
JA: Anything else you want the mechanic to know before I connect you?
Customer: How does the truck maintain fuel pressure with this system? If this is a no-return system, as I see no return from the engine, then why are there 3 lines coming from the top of the fuel pump assembly?