JoeyBagOfDonuts

So I remove valve covers again and found #4 push rod bent. Replaced the push rod and took for a road test. Ticking has gone away but fuel pressure commanded is 580 and is still anywhere from 475 to 610 psi. fuel rail temp is still reading -40. any ideas? Fuel pump control module? Fuel rail pressure sensor?

When keyed on or priming the system the pressure goes upto 80 psi, at idle low side is at 45-55 psi. I’m wondering what would cause the high pressure to vary so much. Commanded is 600ish but it bounces around +\- 150 psi. (25%) which in my mind is huge. My 14 sierra holds steady at 690 psi (commanded is 690 psi). Can I swap fuel pump control module with my sierra or do they need to be programmed? is there an actual fuel temp sensor? I’ve read it’s part of the rail pressure sensor. But can’t find any confirmation. I don’t want to throw parts at it.

I have a 2017 Silverado 1500 with the 5.3. Had misfire on cylinder 4 and p0172 and p0175 codes, had alot of fuel in oil, replaced the HPFP and misfire went away as well as a tick to the engine. Fuel pressure was bleeding off and replaced in tank fuel pump now it hold 80psi. Truck is running better and after resetting fuel trims they have smoothed out and are reading at 0 on both banks. The truck is still not running right and can hear a tick on bank 2. Ive removed both valve covers and cranked the engine over and everything is moving, didnt see anything wrong with the valvetrain. Im not getting any codes either. The rail pressure is bouncing from 450ish to 750ish, where as on my 14 sierra it stays at 690psi dead on commanded. I notice the fuel temp is also reading at -40 but on my sierra it doesnt show a reading for fuel temp. Is there a fuel temp sensor? Could it be the FPCM causing the erratic rail pressure. truck has new plugs and wires, fresh oil change, high and low pressure pumps, new tensioner

I picked up a 2017 Silverado was diagnosed as needing lifters and cam and high pressure fuel pump. I pulled valve covers off and cranked engine over and everything moves and since changing the fuel pump and oil there’s no more misfire codes and the tick has gone away. But the engine still stumbles and no codes come back. I command the pump on and I’m getting mid 50s psi LSFP, and HPFP is 550-750psi both banks and bouncing between that range. If I crank engine over and disable starting I’m getting 430psi and mid 50s psi when letting it sit fuel pressure drops to 12-14psi. I’ve removed spark plugs and scoped each cylinder and checked to see if the injectors were leaking and they are not dripping at all. LTFT are -15/-16. for what I can find online for trouble shooting it says if pressure drops then replace the G17 fuel pump. Is this the in tank pump? If so how would it cause it to run too rich if it can’t keep prime, let alone over fuel. I have no external leaks. Steel line to hpfp was changed and torqued to spec could the fuel pump module be faulty or fuel pressure sensor causing erratic readings and “false” pressure drops as it starts up instantly no extended crank. Do they need to be programmed or can I take the one out of my 2014 GMC and slap it in this one? I have a 2014 GMC with same motor I’ve been using to compare cold start - to temp readings, I’ve swapped all air management sensors to rule out faulty sensors. No change. im doing a compression test right now, when pulling plugs and wires two of them broke. One being cylinder 8 which had a lot of misfire counts when I first hooked upto the truck but. Also could have been cause by previous shop that diagnosed the cam as faulty… oringal faults were p1072,p1075, p0300, p0304 any GM techs care to chime in