Runs rough and throws code with lift pump - Chevy and GMC Duramax Diesel Forum
04.5-05 LLY 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 4 (permalink) Old 10-09-2019, 08:12 PM Thread Starter
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Runs rough and throws code with lift pump

My truck was running like its missing and throws a code for the fuel pressure regulator which i just changed. I pull the fuse for the lift pump and it runs good and no codes.

Any ideas why it does that? It seems like the lift pump is putting out way to much pressure.

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post #2 of 4 (permalink) Old 10-09-2019, 08:20 PM
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Quote:
It seems like the lift pump is putting out way to much pressure.
It's more common than you think.
Volume, not pressure, the CP3 really doesn't need more than 3-4 psi @ idle.
Some will say 8-10 at most, but it screws with the FPR.

Rig up a test gauge at the fuel filter bleed port and see what it's shoving forward.

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post #3 of 4 (permalink) Old 10-10-2019, 07:38 AM
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what lift pump are you running?

2008 Silverado 2500HD CCSB LTZ Diesel
FASS 95 Lift Pump (with Baldwin filters), Edge Insight CTS Monitor on a Windshield Mount, Nicktane Fuel Filter Adapter w/ CAT 306-9199 UHE tertiary fuel filter, Bilstein 5100 Stock Height, Bushwacker Bed Rail Caps, AMP Research Bedstep, Fumoto oil drain valve, Dorman PS Oil cooler, Pioneer AVIC 7200NEX GPS/Stereo, Air Lift LoadLifter 5000 Air Bags.
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post #4 of 4 (permalink) Old 10-12-2019, 02:48 PM
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Quote:
Originally Posted by Hook'em_Horns! View Post
It's more common than you think.
Volume, not pressure, the CP3 really doesn't need more than 3-4 psi @ idle.
Some will say 8-10 at most, but it screws with the FPR.

Rig up a test gauge at the fuel filter bleed port and see what it's shoving forward.
I'm so glad I listened to you about the Kennedy pumps.
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