2011 Duramax Intermittent P0191 Fuel Rail Press Sys

MRneatfreak · February 23, 2014

This is my worktruck, but I put 53,000 miles on it last year. Got 115k on the clock. Been getting the SES light for about 2 weeks, but happened right after an oil and fuel filter change. I had heard stories about off brand fuel filters causing this code, and that AC delco fuel filters were to be used, but have been using Delco filters. Anyway a co-worker drives the same year and model. Said he fixed his SES light and the same code by cleaning the ground on the negative battery cable as well as the ground for the ECM at the same location. So I did that, and the code went away for three days, I'm pretty sure I satisfied the ECM driving parameters, so that all the systems were checked and in operation after resetting the codes, like idling 3 minutes in drive, then accelerating to 55mph at half throttle, and coasting down tow 20 mph then back up to 55, etc.. So the light and code came back, then I filled up at a different gas station and used winterized #2 this time, and the light went within 10 miles, and stayed off for two days, then I pulled a U-turn and the light back on.

So at this point I don't know if I should focus on powers and ground and cleaning corrosion, or replace components. I had a shop change a fuel rail press sensor, that they said was directly related to this PO191 code as well as another fuel filter, but nothing changed.

MRneatfreak · February 23, 2014

So far it hasn't affected the operation of the engine. It does sound a little different at idle and when accelerating. I read a post at a different forum and they said they couldn't go faster than 5mph with this code, and what ulitmately fixed it for them was to replace the fuel regulator. I don't know almost seems electrical to me.

Prokopchuk_9 · March 1, 2014

No warranty?

MRneatfreak · March 10, 2014

Sorry took so long to reply. I'm pretty sure the warranty expired at 100,000 miles, I am at 118,000 now. Shortly after I posted this the SES light turned off for a day, then turned back on for a day then later that same day it turned back off, and has not illuminated since? I guess if fixed itself? I can't imagine that there would be ice crystals in the fuel system as long as I idle this truck in the winter. I guess if it happens again, I'll have them check the fuel pressure.

Prokopchuk_9 · March 11, 2014

Have you taken a good look at the fuel filter housing?? Some of them will develop a leak, this code has nothing to do with the fuel itself. You are losing prime somewhere, just look it up on my EFI laptop. That code is directly related to pressure regulator on bank 2, if it was me I would take it to a tuner that knows a Duramax well. Where do you live? I could probably direct you to a reputable guy that's close to you.

IMO with no warranty, I would rip that junk filter housing out the truck, by pass it and buy urself a good lift pump. A FASS system or airdog, it will hold rail pressure much better, you can run 3 micron filters and it separates all the air/water from the fuel. Best $600 you can spend on any diesel IMO. If I was you I would take a look at the Fuel pressure regulator voltage closely, if it's jumping around erratically that could be your issue. This could also be an issue with a fuel rail itself, I would take it to an actual tuner for diagnostic.

So where do you live?