Dreaded fuel problems AGAIN. Please help. - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 24 (permalink) Old 02-01-2019, 05:44 AM Thread Starter
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Dreaded fuel problems AGAIN. Please help.

Long story short 2003 GMC Sierra has 260,000 miles on it. It has a 3 inch down pipe to 5 inch exhaust, EFI Live by Kory Willis, PPE boost increase valve, cold air intake, CAT fuel filter adapter, and a FASS 150 lift pump.

About 5 months ago I lost rail pressure and it wouldn’t go above 5 kpsi. I already got all 8 injectors replaced about 50,000 miles ago with brand new Bosh injectors. But anyways back to 5 months ago I put a Exergy Sportsman pump in it and ran great again like a brand new truck and he’s rail pressure like it should, however it idled very high and loped from what I assumed was the LBZ fuel pressure regulator.

But it drove fine so I never looked into it.

Now for the last 2 weeks I’ve smelled fuel around the engine bay but haven’t looked into it because it’s been so cold. Now all of the sudden today I’m loosing rail pressure every 2 minutes. It will drop from 22 kPSI down to 2 kPSI and fall on its face for about 10 seconds and then go back to normal.

What else could it be besides injectors or the CP3?
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post #2 of 24 (permalink) Old 02-01-2019, 06:50 AM
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The LBZ Regulator

04.5 CHEVY 2500HD CC/SB LT-Green, 2" Leveling Kit, Bilsteins, Wicked Wheel 2, Boost Stick, 4" MBRP Turbo Back w/ 5" tip, LMM Resonator Box, Airdog LP, PCV reroute, Airbox Mod with AFE Filter, LBZ MP, Fleece Tapshifter, EGR Delete, Edge CTS2, Mishimoto Trans Cooler, EFI Live Tuned/ Idaho Rob,5% tint, 260K and still going strong,
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post #3 of 24 (permalink) Old 02-01-2019, 07:25 AM
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Quote:
Originally Posted by shane1230 View Post
Long story short 2003 GMC Sierra has 260,000 miles on it. It has a 3 inch down pipe to 5 inch exhaust, EFI Live by Kory Willis, PPE boost increase valve, cold air intake, CAT fuel filter adapter, and a FASS 150 lift pump.

About 5 months ago I lost rail pressure and it wouldnít go above 5 kpsi. I already got all 8 injectors replaced about 50,000 miles ago with brand new Bosh injectors. But anyways back to 5 months ago I put a Exergy Sportsman pump in it and ran great again like a brand new truck and heís rail pressure like it should, however it idled very high and loped from what I assumed was the LBZ fuel pressure regulator.

But it drove fine so I never looked into it.

Now for the last 2 weeks Iíve smelled fuel around the engine bay but havenít looked into it because itís been so cold. Now all of the sudden today Iím loosing rail pressure every 2 minutes. It will drop from 22 kPSI down to 2 kPSI and fall on its face for about 10 seconds and then go back to normal.

What else could it be besides injectors or the CP3?
So you never retuned for the LBZ regulator on the Sportsman pump? There is a possibility that you hurt the other fuel system parts with the abnormally high rail pressure at idle... These systems are made for high pressure at a higher flow rate, not high pressure with a low flow rate...

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post #4 of 24 (permalink) Old 02-01-2019, 08:25 AM Thread Starter
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I couldn’t find a way to get it retuned because the shop that tuned it closed down and the guys at PPEI told me I need the flash scanner that originally tuned my truck because the vin is locked to that tool or I need a Brand new ECM. Called the guy who owned the shop and he said he sold all his equipment so there was no way to get it retuned.
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post #5 of 24 (permalink) Old 02-01-2019, 08:32 AM Thread Starter
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Also I checked my balance rates and all are in between -.05 and +.05
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post #6 of 24 (permalink) Old 02-01-2019, 08:52 AM
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If u can’t tune the LBZ regulator then put your LB7 one back in.

04.5 CHEVY 2500HD CC/SB LT-Green, 2" Leveling Kit, Bilsteins, Wicked Wheel 2, Boost Stick, 4" MBRP Turbo Back w/ 5" tip, LMM Resonator Box, Airdog LP, PCV reroute, Airbox Mod with AFE Filter, LBZ MP, Fleece Tapshifter, EGR Delete, Edge CTS2, Mishimoto Trans Cooler, EFI Live Tuned/ Idaho Rob,5% tint, 260K and still going strong,
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post #7 of 24 (permalink) Old 02-01-2019, 08:54 AM
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Ok, lets just start by looking at the codes you have.

P0089 is Fuel Pressure Regulator Performance-which you are going to get since it is not tuned correctly for the LBZ regulator.

P0103 is Mass Air Flow Sensor Circuit High Frequency

P1093 is Fuel Rail Pressure Sensor Out Of Spec which is likely also due to not correctly tuned for the regulator.

U1152 is HVAC communication loss

U1024 is TCM communication loss

So nothing there really that points to a fuel smell or low rail pressure. Clear the codes and see what comes back, see if it changes driveability. You probably wont see any change

If you have a fuel smell around the front of the truck, you need to look into that and see why and where. Having a lift pump on it, it could be pushing fuel out of a leaky hose and not supplying the cp3 with the fuel it needs.

You need to do something about the tuning issue with the regulator, before it causes a bigger issue. Whether its buy an autocal from PPEI or go to a different tuner, or whatever, you need to get it rescaled for the LBZ regulator

Name: Matt
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Play Truck - 2002 LB7 2500HD Crew Cab Short Bed
Daily/Tow Rig - 2006 LLZ 2500HD Crew Cab Short Bed

SOLD - 2007 LBZ 2500HD Standard Cab Long Bed
SOLD - 2006 LBZ 2500HD Crew Cab Short Bed
SOLD - 2004 LLY 2500HD Crew Cab Long Bed
TRADED - 2002 2500HD Crew Cab Long Bed
SOLD - 2001 2500HD Ext. Cab Long Bed
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post #8 of 24 (permalink) Old 02-01-2019, 09:05 AM Thread Starter
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Okay I’m gonna pull it in the shop soon and check the fuel leak and ask around about tuning and get back to y’all. I even asked i could buy a auto cal and PPEI told me it would be a waste of money since the VIN is most likely locked to the auto cal that flashed it originally and even with a new VIN license I couldn’t get past that. However other tuners have told me it wouldn’t be a problem. Maybe the new CP3 is shot? It’s only 5 months old but I don’t think Exergy will warranty it out and I still have $800 to pay on it
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post #9 of 24 (permalink) Old 02-01-2019, 09:13 AM
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Like my boy @DMAXfirefighter said and I’ve said early in the post the LBZ regulator is causing the issues. The cp3 will only supply what the regulator is telling it to. Being the LBZ regulator is an upgrade for us LB7/LLY guys we have to get it tuned. Another thing to check as well would be the return rate of fuel your seeing having been using this regulator for so long. The relief valve could also be weak and smell could be the return lines on the injectors leaking. Either way good luck with it. We’re here to help, but in the end u have to fix it.
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04.5 CHEVY 2500HD CC/SB LT-Green, 2" Leveling Kit, Bilsteins, Wicked Wheel 2, Boost Stick, 4" MBRP Turbo Back w/ 5" tip, LMM Resonator Box, Airdog LP, PCV reroute, Airbox Mod with AFE Filter, LBZ MP, Fleece Tapshifter, EGR Delete, Edge CTS2, Mishimoto Trans Cooler, EFI Live Tuned/ Idaho Rob,5% tint, 260K and still going strong,

Last edited by BlownL36; 02-01-2019 at 09:16 AM.
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post #10 of 24 (permalink) Old 02-01-2019, 10:06 AM Thread Starter
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Oh I also noticed one of the lines from the tank running up past the firewall is kinked.
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