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

Left a VM yesterday with that tech I mentioned, so hope to hear back soon.

I also remembered something else yesterday...your truck has a fuel heater in the fuel filter. So depending how long KOEO, it may have affected the fuel temp. Ignore the fuel temp for now as it has no bearing on what is causing the other issue
 
Spoke with that diesel tech I used to work with last night. Turns out he moved south and has a new phone carrier and #

He agrees with me about being more a mechanical problem than electrical. What he suggests is to tie in some clear hose on the return line at the return junction block. Preferably at the single line for the output for both banks, which is the easiest to do. Then while the condition is present during the cold start, watch for fuel flow. If none or very little, there's the problem. You can then go to the input side of the junction block and put the clear hose on both banks to see if one or both banks are restricted. **edited again to correct the last 2 sentences.

He also mentioned if the pressure relief valve has ever been removed, good chance that's the problem. I don't ever recall replacing or removing one, but he's seen several instances where it was improperly torqued when replaced. While torque is critical and difficult to achieve due to access, he also said its easy to damage during installation. What he does now is just replace the LH rail assembly instead of dicken around with the valve. >edit< A new rail includes the valve installed

Hopefully this will narrow down the cause. If need be, I can swing by and help since having 2 people will make it easier. Or just reach in through the window and start it, then quickly get over to the passenger side to watch the clear hose when that hi pressure is present. Obviously you'll know it if you hear it rattling.

Let me know...
 
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Supposed be ok weather wise this weekend, I will get some more clear hose and report back.

Thanks madhawg
 
Started it up tonight, need to go get some wood pellets.
Threw a P0089 FPR code right away and fuel pressure is at 84mpa(12k psi), desired fuel pressure at 44mpa
Try to clear code it comes right back.
Shut off and restart it won't drop fuel from 84mpa. Desired fuel pressure ar 44mps
This is the same cycle I have been through previously, where it will run ok for 200-400 miles and then go to
complete shit.
Pretty sure it has smoked another fuel pressure regulator.

EDIT: More info, I unplugged the FPR, no change in fuel pressure, I plugged the FPR back in, it stopped
running, still had FPR code (understandable I had it unplugged)
Fire it back up and fuel pressure returned to normal actual and desired dead nuts on.
Cleared code and it hasn't come back.
 
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More info, went a got a ton of pellets from homie depot.
On the way there went to pull out on the main road, fell flat on it's face.
FPR desired was 114 and actual was like 60, got it going enough to get to 45mph said fuck it I'm some pellets.
Watched the actual and desire on the FPR the whole way.
Same deal desired 114, actual about half that.
If I babied it actual and desired stayed close, but anytime it wanted more like a hill it would go to desired 114 and actual 60
It threw a P1087 for low fuel rail pressure, cleared it and kept going.
Got to homie depot, shut it off and went in paid for the pellets, moved so they could load with forklift.
Fired right up, got loaded, went to leave and it fell on it's face, wouldn't rev past 1000 rpms.
Kept stabbing the throttle and got moving pretty good.
Threw a P1093 code, left it and kept headed home.
Couple good hills, just milked it and was able to get home, it actually ran ok on the way home with
actual and desired fuel pressure both matching but I could tell if I asked it for full throttle it wasn't going to happen.
 
Geezus...that rig is possessed! I can imagine the frustration. In fact I've tasted it many many times with those Dmax's, only add in the flat rate clock hanging over your head to really stress you out.

As much as I'd still like to see the results from the clear hose on the return side first...with both hi & lo pressure faults, my next move would be replacing every last piece of rubber hose on both supply and returns. That would include the ones at the tanks, fuel cooler, behind the LH cyl head, at the CP3 pump, fuel filter and fuel rails. I believe you mentioned you replaced some, but make sure you get them all. With that age, any of them could be collapsing or deteriorating internally. I'd also seriously consider replacing the LH fuel rail, since I believe you mentioned you removed the press relief valve at some point. IIRC there is a test you can do that will test the relief valve. I'll have to look it up if you want to test it to be sure.

You're into it this much so far, might as well cover the rest so when you're done, the entire fuel system is brand new which should give you piece of mind and many miles of trouble free driving. The hoses and rail are minimal costs compared to the rest, but the labor is a bit time consuming.

I'm going to the final basketball game for the season my grandsons are playing in at 9, after that I'm free and can swing by your place this afternoon with my Tech2 if needed.
 
I did have one recently at a friend's shop, LLY that wouldn't start after a fuel filter replacement. I was able to prime it by opening the bleeder on the filter housing and pressurizing the tank through the filler neck with a rag, but it wouldn't start after it was shut off. I had him look underneath when I primed it again, lines from the tank were wet. Turns out that the rubber lines from tank to CP3 were dry rotted and sucking air in, even though they looked good externally. Lines were replaced and the customer said it hadn't run that good for a while. Rebuilt the fuel filter prime pump for good measure at the same time.
 
Fuck, durrramaxes are more problematic than the damn old 6.0!
 
DHR Darren said:
Fuck, durrramaxes are more problematic than the damn old 6.0!
Click to expand...

Buddy of mine has an LLY with 350k on it, all original other then maintenance stuff, original fuel system.
That's why I got the same version figured I couldn't go wrong, fat chance.

But then again the guy that hauls all the trucks I buy has a 6 ut oh and it's all original, not sure what it has for mileage
but it keeps hauling shit, he said he isn't messing with until it needs it. Shit it may never need it.
 
I had a 6.0 that I was very lucky with also. It did kill 2 injectors but that was my fault after nearly running out of fuel in the woods one night drinking beer and pumped the last of my off road fuel into the tank. I'm sure I got a bunch of nasty shit water and everything else in there.

Lowrider said:
Buddy of mine has an LLY with 350k on it, all original other then maintenance stuff, original fuel system.
That's why I got the same version figured I couldn't go wrong, fat chance.

But then again the guy that hauls all the trucks I buy has a 6 ut oh and it's all original, not sure what it has for mileage
but it keeps hauling shit, he said he isn't messing with until it needs it. Shit it may never need it.
Click to expand...
 
Fired it up this morning and it's like last night didn't even happen, fuckin whore.
Fuel pressure right where it is supposed to be 44mpa actual and desired.

I have this off my parts engine, I am going to see if I can get that valve thing off and get some fittings
so I can put a hose and gauge on it.
Wonder if that's the fuel temp sensor on there.


 
Yes that is the fuel temp sensor on the opposite end from the vac port.

If you can get all those return hoses in one kit, get it. Individual from GM always took for ever to get.
 
madhawg said:
Yes that is the fuel temp sensor on the opposite end from the vac port.

If you can get all those return hoses in one kit, get it. Individual from GM always took for ever to get.
Click to expand...

On it's way, fuck it what's another $330 :ROFLMAO:
 
Put the new hoses on today, no change.
Desired fuel pressure 42
Actual fuel pressure 81 (I can hear the injectors clacking because of the high fuel pressure so I believe it's reading correctly)

This thing is fucked, I can't even clear the fuel pressure regulator code it comes right back.
Also can't change fuel pressure with the scan tool.
Something is wiping out these fuel pressure regulators, I guarantee if I put a new one on it will be ok for a couple hundred miles
and go to shit.
 
Lowrider said:
Put the new hoses on today, no change.
Desired fuel pressure 42
Actual fuel pressure 81 (I can hear the injectors clacking because of the high fuel pressure so I believe it's reading correctly)

This thing is fucked, I can't even clear the fuel pressure regulator code it comes right back.
Also can't change fuel pressure with the scan tool.
Something is wiping out these fuel pressure regulators, I guarantee if I put a new one on it will be ok for a couple hundred miles
and go to shit.
Click to expand...
Just to be clear...>ALL< the rubber fuel hoses, both supply and returns, are new?
You can't clear the FPR code because its a hard code...fault is currently active.
Not being able to change press is odd. When you attempt to change it, does the Desired press still stay at 81 on the scanner?

Key cycle still fix it like before?
Both rails been removed to clean/inspect and see if any junk came out?

My next move if the rails are clean, is check the FPR voltage at the regulator itself. Get a reading when its running correctly and another when its fucking up
 
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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.
 
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.
 
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