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2005 6.6L Duramax LLY. Truck came in loosing power and setting P1093 c

Customer Question
ode. Fuel vacuum gauge showed...
2005 6.6L Duramax LLY. Truck came in loosing power and setting P1093 c ode. Fuel vacuum gauge showed 3 inches of vacuum at idle and 8-9 at WOT which are all with specs.
We pulled the injectors and had them tested and they all showed excessive return rates. So that is where we started. Put new Bosch injectors in and no change. So we have went down the list from there.
New CP3 Pump
New Fuel Control Actuator
Fuel Rail Race Plug to bypass FPRV
All rubber lines have been replaced from CP3 back to tank.
No kinks in any metal lines.
New Fass Lift pump.
Bypassed OEM Fuel filter housing Completely.
Chevrolet reprogrammed ECM.
Nothing has changed this issue one bit yet.
We have also mounted a small tank under the hood and let the CP3 pull directly from that just to bypass everything back to the tank and that also made no change at all.
If you ease in to the throttle slowly the truck will run fine and make pressure. But if you try to take off moderately hard or smash down on the pedal the rail will jump to 21,000psi and then just plummet down to around 3500psi and have no power at all. Let off and it will recover and if you just ease in to it the rail pressure will climb and it will run fine.
We can also run the pressure all the way up with the Tech 2 and it will hold all day long. The problem is taking off under hard to moderate throttle or while driving down the road if you get in to the throttle hard to pull a hill or pass it will do this.
What the heck are we missing?
Submitted: 2 years ago.Category: Chevy
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Answered in 15 hours by:
6/10/2015
Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 30,463
Experience: 14 years GM dealer Technician.
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My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
If you have not checked the accelerator pedal sensor value to see if it is sending a correct signal when pressing down hard or rapidly on the fuel pedal this needs done.I have seen this sensor act up before which can cause other codes like the low fuel rail pressure to set.
If this is found to be a faulty it will need replaced.If this is found to be o.k. let me know.
Thanks Pete
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Customer reply replied 2 years ago

The APS is fine.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Was the fuel rail pressure sensor replaced at all?
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Customer reply replied 2 years ago

Yes, brand new. I guess I forgot to list that.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Did this model come equipped with a low pressure pump or did you add that yourself?
If you added it was this a problem before the low pressure pump was installed?
Let me know,thanks Pete.
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Customer reply replied 2 years ago

We added the k low pressure after the problem was already there.

The thing is we have bypassed everything from the CP3 back to the fuel tank by placing a small fuel tank under the hood the CP3 is pulling directly from. This did not change anything.

So the problem is from the CP3 to the injectors. But everything there is brand new. CP3, Fuel control actuator, fuel rail relief valve, injectors and all the rubber hoses. There is nothing else to replace.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Did you have the replacement injectors programmed at all?
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Customer reply replied 2 years ago

05 LLY don't have flow programming?

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
My info shows the ID tag still has to be programmed into the computer when the injectors are replaced.This should be the Id tag on top of each injector as there should be a number on each tag to input into programming when they are replaced.I don't recall myself if Ive programmed 05 but my info is showing it is still required.
If this is the cause you may have a fault with them operating incorrectly after replacement causing this fault here.
Thanks Pete
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Customer reply replied 2 years ago

I have never seen LLY injectors have the flow programming. These injectors were direct from Chevy and had no ID tag programming numbers.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
O.k.,then my info is off on this year and injectors.If there is no ID tag then no programming is needed.
Did a dealer check for any updated programming or programming issues at all with the computers?
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Customer reply replied 2 years ago

Yes, we took it to the dealer across the street and they done a full update on it. It is actually over there again now because we got a whole new ECM to try because we are out of options.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
This is a tough one as you have covered everything.If the ECM replacement and programming does not correct this let me know.
Thanks Pete
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Customer reply replied 2 years ago

ECM did not fix the problem. We ended up just leaving the truck with them to see what they come up with.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
Hi,
I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.
Thanks Pete
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Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
O.k.,if there is anything else I can help with here let me know.I can also open your question up for others here to see if anyone else can assist further just let me know if this is something you would like to do.
Thanks Pete
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Customer reply replied 2 years ago

Dealer could not figure it out either. We ended up tearing the whole system apart this morning and found the rail supply line orifices plugged up solid.

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
That is great to hear you have located the fault.I apologize the dealer was unable to help and neither was my info here.If there is anything else I can help with let me know as I strive to achieve an o.k. to excellent rating.
Thanks Pete
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Customer reply replied 2 years ago

How do I get my money back since no one on here helped us?

Chevy Mechanic: Pete, Auto Service Technician replied 2 years ago
I will send this to customer service for you.
Thanks Pete
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Pete
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