2003 vortec 6.0 - fuel pressure problems

[westman995]

I pulled most of the plugs and all of them were more of a white color.. Not brown like i think they should be. So it must be running lean? cylinder 8 was the worst one.

 

[drakon543]

A bad fuel pressure regulator can cause the pressure to be too high or too low depending on which way it fails. There have also been reports on gm pressure regulators having low pressure but the regulator tests perfectly fine. To my knowledge ive only heard of that issue on the gm cars not the trucks. Anyway its actually a small pin hole in the regulator in just the right spot so air is getting pulled into the fuel line. The same problem can also occur in the fuel lines themselves if a pin hole develops in just the right spot.

 

[westman995]

From what I have read alot of people say my fuel pressure would be considered low. Some say it's fine. If the regulator can cause it to be low I think I should maybe try a new regulator. It does not leak fuel and the pressure raises when the vacuum is unplugged so I figure it was fine.

 

[Chizzychase]

Okay so is it sometimes going almost to 60 and sometimes only to 40? or???

because in the initial post it said you were experiencing 40 psi at key on which is low but if its going up to almost 60 (which is normal the spec is supposed to be like 55-62 psi) sometimes then its an intermittent failure somewhere in the fuel system.

I'm just trying to understand whats going on.

 

[westman995]

My original post was before I replaced the cheap pump with the ac delco pump. The pressure is now higher at around 48 while running if I recall.

Weird thing is if I turn the key on it jumps up to 58 or so then drops right down like 10 psi and then it'll slowly bleed off from there.

I ended up ordering a regulator so I'll see what happens after that

 

[Chizzychase]

Yeah the pressure is supposed to drop some when the trucks running but not that much I don't think. I wanna know if the regulator fixes it hope it does

 

[westman995]

It's not even running when it does that. Key on engine off it jumps to full pressure them immediately drops by like 10 psi then from there it will slowly drop pressure.

To be honest I have my doubts about the regulator fixing it but hopefully it does. I'll report back when it comes in

 

[bottomline2000]

I've been chasing a similar issue with my truck. My fuel pressure was around 48 running. Key on engine not running it would jump to 55psi and hold. If I started it and pulled the vacuum line the pressure would bounce back and forth from 45-55 real fast. Took the regulator back and swapped it. Now pressure jumps to 55 and falls to 50 immediately with key on engine off but when I pull the vacuum hose with the engine running the pressure hovers around 55. The truck feels much better driving around town and stronger on the hwy.. hopefully my fuel mileage will be better than 11. I don't think the old regulator was letter the fuel pressure rise.

This was a BWD regulator btw..my Delphi one buzzed so I took it back..it's been a crap shoot with these things..

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[westman995]

Well I put the new regulator in (delphi) and it did absolutely nothing. As far as I can tell it's running lean more on bank 2 so I'm thinking injectors or intake leak. Maybe the cats are plugged. I dono what else to think with this thing. It's just a money pit so far

 

[01ssreda4]

You have a bad check valve. When you turn the key the pump primes, that's it. This lasts a second or two then it shuts off if you dont start the truck. Once primed it should hold pressure for an hour to a week. It should not immediatly start dropping. If it does you have a mechanical problem.