high pressure pump

Furlong2022

New member
Sep 6, 2023
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Deridder, Louisiana
Just out of curiosity i have a high pressure pump out of a 2008 gmc 3500hd thats going out but still works i am curious if it will work on my 2005 chevy 3500 that i believe the pump is out on. does anyone know if they are pretty much the same or if it would work or is it totally different?
 

2004LB7

Well-known member
Dec 15, 2010
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Norcal
I'm pretty sure the only difference is the regulator. Which you can swap between them
 

Ron Nielson

Active member
Oct 11, 2009
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Berryton, KS
When I compare the pictures from the link I posted, there are inlets/outlets present on the LBZ-LMM pump that are not on the LLY. Sure doesn't look look like the same pump to me.
 

Furlong2022

New member
Sep 6, 2023
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Deridder, Louisiana
What’s the actual fuel rail pressure supposed to be on the rail? I’ve been told many different things mine doesn’t build anymore then about 170/180 psi which I know is low I have to prime my system before I can even try to start it which I’m pretty sure is my injectors due to getting diesel into my oil
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
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Central OH
It'll need to build a couple thousand before it fires, idle is around 5k. If diesel is getting into the oil on an 05 LLY it's not the injectors
 
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Bdsankey

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It'll need to build a couple thousand before it fires, idle is around 5k. If diesel is getting into the oil on an 05 LLY it's not the injectors
Agreed. Usually when I see an LLY getting fuel in the oil the main culprit is the front seal on the CP3.

It is possible for the injector to be hanging partially open and draining rail into the cylinder after shut down but that's not a very common failure mode on the later generation trucks.
 

Bdsankey

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So really when I pull my cp3 out that could be the culprit for both issues the no start and the diesel in the oil
Possible? Sure

Guaranteed? No. To 100% solidify what the issue is you need to further diagnose. To check the front pump seal, pull the oil fill tube or put a camera down in there and see if you can see fuel spraying behind the CP3 drive gear.