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2017 5.3L Running rough

JoeyBagOfDonuts
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JoeyBagOfDonuts New Member

JoeyBagOfDonuts

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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

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

80 psi is really high for the low side fuel pressure. The fuel pump control module should be controlling the pressure based on demand. At idle it's only going to need 42-45psi on the low side and it should bounce between that 45-60psi while normal drive and may spike above that at wide open throttle.

JoeyBagOfDonuts New Member

JoeyBagOfDonuts

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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.

JoeyBagOfDonuts New Member

JoeyBagOfDonuts

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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? 

  • 8 months later...
Jayson h New Member

Jayson h

Posted
Posted
On 5/23/2024 at 7:50 PM, JoeyBagOfDonuts said:

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.

Have you found your issue? I have exact problem with erratic rail pressure

GMCustomerService Senior Enthusiast

GMCustomerService

Posted
Posted
On 1/31/2025 at 3:16 PM, Jayson h said:

Have you found your issue? I have exact problem with erratic rail pressure

We regret to hear that you are facing concerns with your vehicle and would like to investigate further on our end. Please send us an email to [email protected]. Be sure to include your Username and Forum name in the subject line with additional details. We will watch for your email. 

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