06 LBZ P0087 Headache

TheBac

Why do I keep doing this?
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Apr 19, 2008
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I would RUN (not walk) away from Diesel Logic, Injectors Direct, Pensacola Diesel. I have sold a few of the Industrial Injection reman pumps and they've been decent. Bosch also does offer a reman themselves which is a pretty darn good pump.



^This. While I personally won't say it, I know myself and the other vendors greatly appreciate the business. Supporting this page is not free and I know I personally am not a supporting vendor for the monetary aspect. I personally learned A TON from this page and I want to help keep it going for those who join.

I am also a site sponsor to try and ensure people don't get screwed over or sold a crap package of parts that won't meet their goals. Old school? Sure, but god it's nice when a customer gets a matched set of parts and it meets their goals.
I cannot "Like" this post enough. (y)
 

Kdub613

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Sep 21, 2023
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I haven't had the time to really do a return test, but managed to have the time to do an injector cleaning (smh) with the AcDelco 10-3015 stuff. It seemed to help. The worst injectors I had were #1 and #2 and they sat at -3. once complete #1 was -1 and #2 was -2. All other cylinders were between -1 and 1. Seems to be well within the normal specification range.

Next on the list is going to be the return test and a CP3.
 

Kdub613

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Sep 21, 2023
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Wanted to provide an update and additional issues I need advice on. There was a lot of recommendations to replace the CP3. I spoke to a few diesel shops and they said injectors before CP3. I went with new injectors. The P0087 hasn't come back on since and the truck runs good.

Just recently, hooked up my lift pump back up (verified 10 PSI to the fuel head assembly), and now I get a P0088. I hooked up my cheapy scan tool and watched the Actual Fuel Pressure increase at idle (cold). It started at 4800 and just climbed up to 9500, then the light would come on. I cleared the code thinking it was a hiccup and it did it again. I shut the truck off cleared the code again and then the truck wouldn't start.

I opened the hood and the fuel head assemble lost its prime. I re-primed the unit and it fired up and ran well.

I am at a loss at this point. I already replaced the FPR on the CP3. I was thinking of replacing the FRP Sensor. I don't know about the fuel head assembly though. The O-ring around the bleeder is new, there are no leaks around the unit either. The Fuel Head Assembly is new as well since I was chasing a rabbit with the P0087. I also replaced the fuel lines from the Fuel Head Assembly to the engine. I did this as I was already in there and it made sense to get them replaced.

Any thoughts or suggested areas to look at would be greatly appreciated.

Thank you in advance.
 

darkness

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Jul 15, 2009
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You shouldn’t have lost prime with a lift pump. You need to check the lift pump pressure and make sure it’s not too high. It’ll make your fuel rail pressure go up if it is.
 
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Kdub613

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You shouldn’t have lost prime with a lift pump. You need to check the lift pump pressure and make sure it’s not too high. It’ll make your fuel rail pressure go up if it is.
I have a fuel pressure gauge on the lift pump and it verifies at 10 PSI. The odd thing was, I just drove the truck an hour earlier and parked it for baseball practice. When I left, I turned the key waited 3-5 seconds, and tried to start it....just cranked over. I did this twice. When I popped the hood, and checked the fuel filter assembly, it was super soft. I Pumped it up 10 times and then it fired up.

Just last night, I checked around the filter assembly and it was a little wet, so I replaced the filter assembly (lifetime warranty). Primed it, truck fired up great. Come to this morning, after letting the truck sit for a 8 hours, I popped the hood and checked the filter assembly, the plunger pushed right down. I didn't start the truck as I have a company truck and needed to get on the road, but I wanted to see if it held pressure overnight.

Should the plunger always remain stiff even after the truck has been sitting? If not, there has to be some leak somewhere? Then again, there is no fuel leaking on the low pressure side (the lift pump would tell me that). Injectors are brand new (1.5K miles on them), FPR is new as well. I have new fuel lines from the Filter assembly to the CP3.

Could a sticking FPR cause fuel to leak back to the filter assembly?
 

2004LB7

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Primer bulb will go soft overnight. Pretty normal. Bit as long as the lines are still full of fuel and not air then it isn't a problem.

How is your lift pump wired? Does it not turn on with the ignition and pump up the filter housing and thus primer bulb?
 

Kdub613

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Sep 21, 2023
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Primer bulb will go soft overnight. Pretty normal. Bit as long as the lines are still full of fuel and not air then it isn't a problem.

How is your lift pump wired? Does it not turn on with the ignition and pump up the filter housing and thus primer bulb?
When I turn the key to on, the lift pump starts up. It seems that it takes a minute to prime itself, then the fuel filter head.

I am gonna see how it starts this afternoon since it has been sitting for 18 hours.

It was odd, because right before all of this, I had a P0088 code....which didn't make any sense to me. Trying to understand the P0088 is the next challenge.
 

Bdsankey

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If it's taking a bunch of time to prime the lift pump itself that is not a good sign and means there is an air or fuel leak on the suction side of the pump if what you're saying is accurate.

If the pump sound doesn't change but it takes a moment for fuel to say come out of the test port, that implies there is an air or fuel leak somewhere between the lift pump and the engine and thus can cause your issue.
 
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N2BRK

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Dec 31, 2009
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Not to side-step good diag/repair, but why not put a barb end on the Cp3 and run the FASS directly in. You have no need for the fuel head and OEM filter any more. Eliminate all of it. Then see if you still have an issue.
 

darkness

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I’ve deleted the factory filter on all my trucks with direct feeding the cp3 on 2 of them. Sean did the ‘02 when he owned it still.
Something else to try, pull the fuse on your lift pump and see if the pressure drops to commanded. I don’t remember if the FASS is of the pass thru kind? Easy way to start eliminating things.
 

Kdub613

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Sep 21, 2023
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I want to start off by saying THANK YOU to all on the forum and provided input and things to look for. I have checked over everything and that seems to check the box of potential issues was the FPR! I bought a new Bosch FPR and installed it. Truck runs really good. I am hoping this is it.

Thanks guys!
 
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Kdub613

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Well the FPR might not be the ultimate fix. Wife was driving the truck home last night and was starting an uphill back road to the house doing about 20-25 mph (in the stock tune - don't really use the tunes on the truck) and DTC - P0087 popped up. It appears the code pops up randomly.

At this point, everything has been replaced except the CP3 pump. 😕

I am at a loss and this is becoming extremely frustrating.
 

2004LB7

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If it was me I'd tune that out, or at least open up the perimeters needed to trigger it
 

Kdub613

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If it was me I'd tune that out, or at least open up the perimeters needed to trigger it
I bought the truck with EFI Live already installed and I don't have the EFI Live tool to adjust it. It never came with the truck.

Any thoughts on how to get that done?

I am almost at the point of doing the CP3 and flashing the ECM back to stock.
 

Kdub613

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Have you logged the truck when it occurs? IE to see what desired and actual rail pressure are doing?
I have previously, but not recently. Previously, the desired would be 26K and actual would be around 16k.

I will try this weekend and see If I can monitor it.
 

2004LB7

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I have previously, but not recently. Previously, the desired would be 26K and actual would be around 16k.

I will try this weekend and see If I can monitor it.
That makes me think, based on what you have done so far, that the CP3 is weak or the tune has been botched
 

Bdsankey

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That makes me think, based on what you have done so far, that the CP3 is weak or the tune has been botched
I agree. This is what we all thought back in 2023 as well.

I'm wondering if the new injectors masked the problem some and it's finally popping back up.
 
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