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04 4.8 fuel pressure regulator

Scott Mclay
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CamGTP
CamGTP

There isn't one. The returnless fuel system as the regulator built into the fuel pump.

CamGTP
CamGTP

No not really.   Investigate the lean code. Could be anything from the intake gasket leak to an exhaust leak on the exhaust manifolds before the o2 sensor.   Intake gaskets are eas

CamGTP
CamGTP

It's a rubber o-ring style gasket, they flatten out over time along with all the hot/cold cycles. It's going to cause a leak someday.

Scott Mclay Enthusiast

Scott Mclay

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I am going to have it diagnosed during the week it runs a little better but it still has a hesitation off subject I have a manual 2-speed transfer case 4hi 4lo what kind of fluid does that take I don't think it's Auto Trak I think it's Dex 3

davester Senior Enthusiast

davester

Posted
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Yes, it should be DexIII.  And you want to find an actual DexIII fluid, as while DexVI is considered compatible, it was found to leak past seals when put in earlier vehicles.  GM changed their seals when they switched to DexVI.

davester Senior Enthusiast

davester

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Also check fuel pressure at the rail, both at idle and when the engine is revved up.  Pressure should be right around 60 psi, just going lower when the engine is revved, but quickly returning to full pressure when the speed levels out.

 

When I first got my truck, it acted similarly, and for me, it was the fuel pump failing, exhaust leak due to broken off bolts, and O sensor.

Scott Mclay Enthusiast

Scott Mclay

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Davester, how was your truck when you got it and what year mine is o4 with 185000 miles, just for a work truck but when im on the highway in 4 th with the converter lock under a load it craps out unless i kick down to 3rd its the shaking thats really bothering me plus the idle seems low and rough, thanks you guys

Scott Mclay Enthusiast

Scott Mclay

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I have new fuel pump, new plugs, new intake gaskets and a new map sensor.the guy i got it from said he put a new fuel pump in but what kind i dont know.  With my last work truck it was an 09 i was told only use delphi pump

davester Senior Enthusiast

davester

Posted
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When I first got my truck, before I fixed it, it would drive ok, but just guzzle gas, as it both had an exhaust leak, and low fuel pressure, so the ecm was dumping as much gas as it could into the engine.  It shifted fine, but had no power (as the gas was being dispensed, but poorly, as there wasn't enough pressure to atomize it properly).

 

I think the main things that fixed it for me were:

-replaced fuel pumps (mine has two, only one is really important)

-fix exhaust leak by replacing broken exhaust bolts and/or installing clamps for the ones that couldn't be readily fixed
-replaced MAF and upstream O2 sensors

 

I also replaced other stuff, but I don't think they had much effect (as in, they weren't an actual problem):

-knock sensors

-intake manifold gaskets

-spark plugs

-MAP sensor

Scott Mclay Enthusiast

Scott Mclay

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Jasta update you guys that helps me out it was the number 7 injector and the evap purge line was broken where it goes back behind the engine so truck runs very well thank all of you for your help

  • 3 years later...
Mobile garage New Member

Mobile garage

Posted
Posted

04 silverado 1500- yes it does have a regulator first off. You have to take the spider box off and it's on the rear side of the injector rail casing held on by a double c clip, problem is, they don't have the one that comes out the 4.3L motors anywhere. The ones they are selling as 4.3L regulators, are for a different v6 than what's in this truck. And everywhere sells only the one. I am looking for the exact regulator I have in my hands. Anyone been down this rabbit hole yet? Or do I have to chase my tail to find one. Please respond. Thanks

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