Woes with a 2004.5 LLY Dmax repeated P0089 Fuel pressure regulator codes.

Lowrider said:
All rubber lines replaced except the one u-shaped to the return and the 2 next 2 the L/S cylinder head.
Return is fine, fuel is streaming out. I might replace the feed line by the L/S cylinder head tomorrow
I even ran the return to a jug, no change and it filled the 1 gallon jug in a few minutes, there is no blockage.
It was a steady stream coming out of the return.
Didn't remove fuel rails, too much work to deal with right now.

Only way right now to get it running correctly is to change FPR.
This is the same cycle I have been through since last year.
Running like total garbage, change FPR it runs fine.
How do rubber lines fix themselves if I change the FPR.

Key cycle does not fix it. Stays at 42 desired and 81 actual.
Unplug FPR nothing changes, I think it's pegged at max pressure.

I was able to change fuel pressure with scan tool previously but now I can't, FPR doesn't respond at all.

This is what I am thinking for next steps.
Put another new FPR on it and swap ECM to a used spare I have and see what happens.
Click to expand...
I glazed right over the steady stream from the return. That sounds like too much without seeing it in person
 
madhawg said:
Refresh my memory...how did every FPR you removed look? I seem to recall a pic of one with junk on it. Did they all have junk? Just thinking out loud...

I won't disagree with another FPR and ECM. But if its hard broke right now, I'd spend some diag time and make sure the circuit is at the correct voltage. You want me to stop by? Say the word and when, and I'll bring my Tech 2 and Fluke.
Click to expand...

The FPR's look fine, but some I have taken out when you shake them you can hear them rattle.
I brand new one doesn't rattle.
Some I have taken out don't rattle but show bad.
 
madhawg said:
I glazed right over the steady stream from the return. That sounds like too much without seeing it in person
Click to expand...

It might but the fuel pressure is stuck at almost 12k PSI and the injectors are chattering/clacking so not only
it the reading correct but the way they sound backs up what the sensor is saying.
 
The source of the noise is all the excess fuel igniting in the cyl, not so much the injectors. I'd be curious to see what the injector voltages are, should be about 50V
 
Lowrider said:
This thread mentions the FPR getting stuck, he had other issues though.

www.dieselplace.com

LBZ: - Changed FPR now won't start

www.dieselplace.com www.dieselplace.com
Click to expand...
Interesting read, especially about the Cascade Overflow Valve. And don't ever recall having a problem caused by that valve either. I found some more detailed info about it elsewhere, so I'll have to go back and continue reading.
 
Lowrider said:
Man I'd love to but with $15k into this heaping pile of shit I just can't.
Click to expand...
You need to get ahold of the gooks who own Evergreen shipping. They just managed to do a second ship.
 
From some info I found about the Cascade Overflow Valve:

"Stage 3
When fuel pressure exceeds 12.4bar (180psi), the spool-piece aligns with the overflow passage. This stage relieves the pressure into an overflow circuit that sends the fuel back to the inlet side of the gearotor pump, thus limiting maximum fuel pressure to 12.4bar (180psi).
Lubrication fuel continues to flow through all channeled passages during this stage.
Excess fuel is sent back to the fuel tank through the fuel-return circuit
Stage 3 is reached at over-pressure"

Which would account for the return volume you mentioned.
 
The brown/white stripe wire has 11.66 volts showing.
From what I have seen it should be 5 volts, not 100% sure though. Over on DRP, SRGN posted up what the voltages should be but they are gone.
Black is ground and Yellow shows nothing


 
I'll look it up, pretty sure its supposed to be ign voltage
 
Took me a bit to find it...its supposed to be batt voltage or as I called it: ign voltage. GM's SI info is lacking so I found it elsewhere:

The electronic fuel pressure regulator is controlled by the PCM. A battery voltage signal and a ground signal are used to control a servo motor which positions a valve so that the desired level of fuel pressure can be achieved for any given set of circumstance. As voltage is applied to the electronic fuel pressure regulator servo motor, the valve is opened in small increments and fuel pressure is increased. When voltage is decreased, the servo retracts and a strong spring forces the valve to close; fuel pressure is decreased.

What needs to be done is back probe it while its connected. Get a good reading when running correctly and then again when its acting up. You said its stuck running poorly, is it still?
 
FWIW...the ecm connector is not for a 2004 and the FPR terminals are in C1 not C2 as the link shows.

Take a test light and connect it to the batt B+, the probe the yellow wire. Do this with the connector plugged in and disconnected
 
madhawg said:
FWIW...the ecm connector is not for a 2004 and the FPR terminals are in C1 not C2 as the link shows.

Take a test light and connect it to the batt B+, the probe the yellow wire. Do this with the connector plugged in and disconnected
Click to expand...

Are they C9 and C10 like this diagram shows?


 
Have a surprise Bday party planned for my wife shortly, so gotta bail. I'll check back later. Do the above test light check and also get the voltage for both the yellow and purple/white while backprobing with the FPR connected

Edited to add: do this at the FPR itself not at C107
 
Well this is interesting.

11.6 volts on the brown/ white stripe wire goes down to 2.2 volts with FPR plugged in

So for giggles I pull the wire off the FPR on the truck and plugged all 3 of these FPRs that I have.
The one marked Rock Auto is brand new, just took it out of the sealed wrapper.
The old brown colored is one of the originals I had.
The new looking one not sure what the story is on this one, but when I shake I can hear something rattle.
The other 2 don't make any noise.

So with the brown and new looking one voltage didn't change.
But with the new Rock Auto one plugged in, it vibrated, first time I have ever noticed this.
Voltage readings were still the same.
So that vibration must be the pulse modulation happening.
I know 100% if I put this one on it will run fine, but I need to find out what is causing these to go bad.
 
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