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Discussion Starter · #1 ·
Hey guys, just picked up a new to me 06 LBZ auto truck! Got a good deal on it but it is throwing the dreaded p0087 code. So far the previous owner has put new filter head, several filters, replaced rubber lines from the head forward but not the ones back to the tank.
The truck right now is 100% bone stock with 220k on it. No injectors or cp3 has ever been changed. I have a PPE xcelerator here that eventually will go on it but I want to iron out the issues first.
Through the ppe I can see the balance rates, at least it says inj 1 bal so I'm assuming that is what it is.
Here are those numbers I pulled today.
P/d
1. -1.00mm -2.5mm
2. -.5mm. -.4mm
3. 1.8mm. 3.0mm
4. -.9mm. -2.5mm
5. 1.6mm. 2.1mm
6. -.9mm. -2.5mm
7. 1.5mm. 3.9mm
8. -.9mm. -.9mm

I understand that balance rates are only part of the issue, but in looking at the fuel rate that it displays in the PPE it stays at 20mm sometimes dropping to 19.5mm in drive, park doesn't matter. Desired and actual rail pressure match at idle.

This things smokes like a freight train under hard acceleration and will throw the code every time. Even under light throttle it smokes a ton!

Things I plan to do is change the rubber lines (they are needed anyways)
Bottle test


What's already done is the above from PO and this
Air filter is new as well as the air filter housing modded
Cleaned MAF sensor

Truck runs good no smell at idle no smoke after it starts

Rail plug is scheduled to be delivered today


Any input on where to go or what to look at next? I'd like to throw a lift pump on it but I'd also like to nail down the issue so I can drive the truck first! Any help is appreciated! Thanks
 

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If its smoking like a train and throwing that code with no tuner then it is most likely high return rates on the injectors or possible even a cracked body or nozzle.
 

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If you change the two 1/2" braided fuel lines between the tank and the filter head, one at the LR of the engine and one below the drivers side that may fix it. Here is a thread telling about that mod:

Read this entire thread:

https://www.duramaxforum.com/forum/...powertrain/431146-p0087-code-help-please.html

Another good link:

https://www.duramaxforum.com/forum/...-fix-p0087-when-under-load-9.html#post5643426

It can also be the braided hose from the top of the tank forward. Also possible is a crack in the fuel pickup inside the tank. this is most evident if the problem only starts when the fuel level drops below the crack in the pickup. A quick check would be to fill the tank and see if it happens immediately.

This is not on your subject but since you are new to these trucks you should also read this thread. It has LOTS of good info you will need:

https://www.duramaxforum.com/forum/maintenance/988217-maintenance-info-suggestions-new-owners.html

MOST IMPORTANT LESSON....................SEARCH is your friend. I found those links in less than 2 minutes
 

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Discussion Starter · #4 ·
I have searched for days, I saw the rubber lines it’s in the original post to be changed, it has the issue full fuel tank or not, doesn’t matter.

My plans are to change the lines, change the rail fitting, possibly port the other one while I’m there.
Add a lift pump
Then see about swapping injectors the others are needed anyways so not really money wasted. I just want to be sure before I drop quite a chunk down on new injectors and they aren’t the issue.

I don’t want to come across as someone who doesn’t appreciate the help, and I’m not new to these trucks. I’m only wondering if there are more issues than the rubber lines, FPRV, CP3, filter head/filter, pickup, and injectors
It seems everyone’s fix for this is a little different. I was confused as to why the PPE would say the fuel rate is 19.5-20 if at idle shouldn’t it be around 9-10 on an LBZ because of the load true turbo gives it? I know LB7 is around 8. Maybe I’m reading that wrong
 

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I have searched for days, I saw the rubber lines it’s in the original post to be changed, it has the issue full fuel tank or not, doesn’t matter.

My plans are to change the lines, change the rail fitting, possibly port the other one while I’m there.
Add a lift pump
Then see about swapping injectors the others are needed anyways so not really money wasted. I just want to be sure before I drop quite a chunk down on new injectors and they aren’t the issue.

I don’t want to come across as someone who doesn’t appreciate the help, and I’m not new to these trucks. I’m only wondering if there are more issues than the rubber lines, FPRV, CP3, filter head/filter, pickup, and injectors
It seems everyone’s fix for this is a little different. I was confused as to why the PPE would say the fuel rate is 19.5-20 if at idle shouldn’t it be around 9-10 on an LBZ because of the load true turbo gives it? I know LB7 is around 8. Maybe I’m reading that wrong
Balance rates are -4 to +4 normal. I don't see any bad, and only one close at 3.9 but still in spec. Before you go spending the money to change injectors Id consider two things.

1. an Injector cleaning procedure:

https://www.duramaxforum.com/forum/...93-how-diy-injector-cleaning.html#post1017269

You can also run Bio Diesel. It not only adds the lubricity back that is taken out in making the ULSD we all must run now but it also is an excellent fuel system cleaner, to include your injectors
 

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Discussion Starter · #6 ·
Balance rates are -4 to +4 normal. I don't see any bad, and only one close at 3.9 but still in spec.
You’re right, the 3.9 was in drive though so still within spec. Today I should get time to swap out the Hoses and see, I’ll inform of the results nonetheless
 

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If its smoking like a train and throwing that code with no tuner then it is most likely high return rates on the injectors or possible even a cracked body or nozzle.
Or an additional problem with air (lack of boost, boost leak, up pipe leak, etc.)

OP, if you want some reading on it, use the advanced search feature with my User Name and posts regarding P0087. Years of posts on the subject (I've done some chasing on it).
 

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Discussion Starter · #9 ·
Or an additional problem with air (lack of boost, boost leak, up pipe leak, etc.)

OP, if you want some reading on it, use the advanced search feature with my User Name and posts regarding P0087. Years of posts on the subject (I've done some chasing on it).
I’ll dot that for sure, I’ve read some of your stuff on it already! If only you were closer to Fort Worth lol
 

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Discussion Starter · #11 ·
P0087 is the only code?
Yes sir, another thing, it sat for almost a week before I started it again today, it cranked for a really long time before it caught. I shut it down and then let it sit for a while, limped the primer to see (4x till firm) and it still cranked a long time. After I changed out the rail plug it cranked for the same amount of time with no fuel in the rail to start as it did before I started working on it if that makes sense
 

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You lost prime on the filter head.....IIRC, you mentioned a new head (not rebuilt), so I would look further down the line towards the tank for a leak, sucking air.

Was/is the tank full? If @ 5/8-1/2 on the gauge, it could be a problem with the fuel module in the tank leaking, sucking air at lower tank levels.

However, as you might have seen in searched posts, it's not always just one thing. It can be 1 of 6, or a combo of all of the above. A little leak here, a bit more there, and the CP3 (old/worn) can't keep up, especially when the fuel gets hot (leaks expand).

If only you were closer to Fort Worth lol
By TX standards....that's just across the street. :teehee
 

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Discussion Starter · #13 ·
You lost prime on the filter head.....IIRC, you mentioned a new head (not rebuilt), so I would look further down the line towards the tank for a leak, sucking air.

Was/is the tank full? If @ 5/8-1/2 on the gauge, it could be a problem with the fuel module in the tank leaking, sucking air at lower tank levels.

However, as you might have seen in searched posts, it's not always just one thing. It can be 1 of 6, or a combo of all of the above. A little leak here, a bit more there, and the CP3 (old/worn) can't keep up, especially when the fuel gets hot (leaks expand).


By TX standards....that's just across the street. :teehee
You’re right there lol it’s a big place!

So it doesn’t matter if the fuel is hot, cold I can start it up and immediately make it throw the code. I’m leaning towards a fuel/air leak is a major issue. Only a few of the lines have been replaced and the new 1/2” hose hasn’t arrived yet. I don’t want to shotgun the issue and throw a ton of crap at it, I would rather figure out the real issue at hand. That is why I’m doing one thing at a time instead of just throwing a lift pump on, then injectors and hoping.
 

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That's the correct way to proceed. Solve the leak issue before you band-aid over it with a LP.

You can start with the filter head, verify that it's not leaking. Remove the input supply line (there's an arrow on top of the casting), slide on a test length of 1/2", into a container of fuel.

Try and duplicate. This will rule out the filter head still leaking.
Then start working your way back to the tank, starting with that supply line you removed (pass side), then the quick connect on the top driver's side, and on back to the fuel module, testing along the way.

Currently in my chase (not consistent limp like yours, comes and goes), I'm suspecting the fuel module. At the very least, if I replace it, I'm not really throwing parts at it, as it's always way off with the level sensor, which affects the DIC %.

Maybe I can at least get rid of that annoyance.
 

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Discussion Starter · #15 ·
That's the correct way to proceed. Solve the leak issue before you band-aid over it with a LP.

You can start with the filter head, verify that it's not leaking. Remove the input supply line (there's an arrow on top of the casting), slide on a test length of 1/2", into a container of fuel.

Try and duplicate. This will rule out the filter head still leaking.
Then start working your way back to the tank, starting with that supply line you removed (pass side), then the quick connect on the top driver's side, and on back to the fuel module, testing along the way.

Currently in my chase (not consistent limp like yours, comes and goes), I'm suspecting the fuel module. At the very least, if I replace it, I'm not really throwing parts at it, as it's always way off with the level sensor, which affects the DIC %.

Maybe I can at least get rid of that annoyance.
That’s a good idea, I was just going to start swapping lines out when the hose gets here tomorrow, but for diagnostic purposes I think I’ll bypass that and run it off of a tank in the bed and see what happens. Thanks for the tip! I don’t know why I didn’t think of that before, only makes sense to do that
 

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Your test source container doesn't need to be large.
At idle, it takes 1-2 hrs to burn thru a whole gallon.
 

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Discussion Starter · #17 ·
Update, tried to run it into an external tank. I primed until I had pumped out about a half gallon of diesel and it would not catch. I had a carter fuel pump that I put in line. Primed with that and it finally fired up. So I changed all the fuel lines, and thought I had the pump that I might as well install it. ran it in line now it starts ok. I can still drain the rail when I floor it for extended time. but now that it is getting fuel I really wonder if it has a tune on it. it is faster than my LB7 was with EFI live by Idaho Rob with stock trans safe tunes. the black smoke isn't nearly as bad now but still there. I can break the tires loose on dry pavement and burn them for quite some time if I want to.
My thoughts are, it wasn't getting the fuel before the lift pump due to collapsing lines, now its getting fuel. now that it is getting the fuel that it wants the power really came to life. but where it is still draining the rail under WOT there is obviously an issue with either the tune, injectors, or CP3 failing. desired rail pressure keeps up until WOT then after so long plummets.
I don't like that there may be a tune on there that is unknown. is there a way to get it back to stock? maybe a dealer reflash? Kinda hard to diagnose when you don't know what's done to the truck.
I think my next steps are to check the return rate while cranking. if it is excessive I will isolate the CP3 and Injectors and measure them individually. If it ends up being injectors then go from Drivers to passenger side to narrow it down further. I also purchased a block off fitting for the injector lines. once I find one side that is returning too much I will use it to find what injector is the issue if any.
 

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It's never just one thing, it seems.
Knock one out, move on to the next.

It would be nice if there was something like a checksum feature to verify stock or mod tunes.
 

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Discussion Starter · #19 ·
It's never just one thing, it seems.
Knock one out, move on to the next.

It would be nice if there was something like a checksum feature to verify stock or mod tunes.
agreed, Maybe its the difference in LBZ and LB7 but I really don't think the power difference is that great. I would imagine some but a tuned LB7 should be faster than a stock LBZ IMO. Oh well, on to the next diagnostic method and see what I can find.
 

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agreed, Maybe its the difference in LBZ and LB7 but I really don't think the power difference is that great. I would imagine some but a tuned LB7 should be faster than a stock LBZ IMO. Oh well, on to the next diagnostic method and see what I can find.
IMHO, unless you know who wrote the tune, and it seems pretty obvious it is tuned, and with a fairly hot tune at that, you would be much safer to simply get a stock or Trans safe tune from a reputable tuner.

A dealer would not be able to load a tune that would allow for the delete of the EGR.

This may even save you money if you find the rail drain issue goes away with a lighter tune. In addition, unless the xmsn is built to handle the extra HP then it is only a matter of time before you are spending $5000 or so on that with your current tune.

Just my .02
 
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