Dropping rail with 3 CP3s?

[DPC]

Having a rail pressure issue with my triple CP3 setup.

Pumps: Valley pump is a reman II 45% with about 68K and 7 years old. It feeds the stock location LB7 distro block.

2nd pump is a 6.7 CP3 with about 48K feeds the back of the passenger side rail.

3rd pump is a LBZ pump with about 50K miles and feeds the front side drivers side rail.

Injectors are big 400% range.

Testing was done on the dyno, 3rd gear converter locked (47RE) starting run @ 2k rpm. In the log rail starts to drop almost immediately about 2500rpm and then the violent shake associated with a drained rail. Max pulse in the tune is 2000us and fuel psi is @ 25.5K.

If I ease into the throttle (about 10-15% throttle max) truck will go to about 4800rpm without an issue, but WOT will drain the rail.

With one pump feeding each rail and the valley pump split between the two rails cause a pressure issue if the valley pump was weak, or are the injectors just too big?

Thanks for your time.

 

[CaptPhil]

Have you tried a smaller tune?

I had problems with rail with my duals, turned out to be regulator tuning issues.

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[DPC]

Log files

Two logged runs attached.

 

[DPC]

small tune

Have you tried a smaller tune?

I had problems with rail with my duals, turned out to be regulator tuning issues.

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That was the small tune, but something to look at. 2000us is only about 500 higher then stock. Getting back on the dyno is not a small task so I need to run through a punch list before I get back on.

 

[x MadMAX DIESEL]

Cp4 the same regulator signals as the cp3?


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[CaptPhil]

That was the small tune, but something to look at. 2000us is only about 500 higher then stock. Getting back on the dyno is not a small task so I need to run through a punch list before I get back on.

Haha I see. I only ask because my truck was well over 1000hp on a 1900us tune with much smaller injectors.

My small DD tune was a 1050 us.

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[DPC]

Cp4 the same regulator signals as the cp3?


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Yes very close. The scale on my tune is also adjusted to compensate for the modified II regulator. This is what I run in table B1010.

1800.000000
1648.500000
1488.750000
1326.750000
1215.750000
1159.000000
1121.500000
1088.000000
1056.000000
1020.000000
1000.000000
993.000000
986.000000
930.000000
878.000000
826.000000
770.000000
601.000000
400.000000

 

[DPC]

Haha I see. I only ask because my truck was well over 1000hp on a 1900us tune with much smaller injectors.

My small DD tune was a 1050 us.

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Wow, very interesting! I had no idea large injectors could make that much of a difference. The biggest injectors I have worked with were only 50% over.

 

[DPC]

Torque tables and Duraflite?

Since I no longer have an Allison telling the ECM torque values and everything Allison related turned off in the DTC files how does this play into tuning the torque tables? I noticed in the logs the TQ value doesn't change in the runs.

Still doesn't change the fact the desired and actual rail are way off, just thinking out loud.

 

[Ne-max]

Running the right controller?

 

[x MadMAX DIESEL]

The Allison in park would full fuel!! don't know about how you did yours up if you removed tcm? Regardless not the problem if it's asking for pressure and not getting it


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[Yellow Jacket]

We run 3 cp3's on our 3.0 truck....we ran a 2000hp 4.1" single turbo with 2200us on 400% Exergy injectors, held 30,000 psi....

What lift pump and fuel feed setup are you running? Can you get/keep enough fuel to the cp3's under WOT?

 

[DPC]

Running the right controller?

Fingers made the controller for me, seems to be working correctly. If I unplug a pump rail shoots up, plug it back in and rail is back to normal.

 

[DPC]

We run 3 cp3's on our 3.0 truck....we ran a 2000hp 4.1" single turbo with 2200us on 400% Exergy injectors, held 30,000 psi....

What lift pump and fuel feed setup are you running? Can you get/keep enough fuel to the cp3's under WOT?

I am using two FASS 150s with AN -10 feed lines up to the engine which then splits into three AN-8 feed lines, one per pump. I have a digital lift pump gauge, idles @ 11psi and has not dropped below 9psi.

How are your high pressure lines routed? Thanks.

 

[Ne-max]

Fingers made the controller for me, seems to be working correctly. If I unplug a pump rail shoots up, plug it back in and rail is back to normal.

Im not sure how different it is but with my dual fuelers it acted the same way. Lb7 controller on my lbz.

 

[DPC]

Switching controllers fixed your problems?


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[Awenta]

Curious why you're using a cp4? With so many of then grenading and destroying the rest of the fuel system along with it.

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[DPC]

It's what I had on hand at the time. First hearing of stock cp4s having problems.


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[juddski88]

Also just thinking out loud, but do you think it would have something to do with the difference in the pumps output frequency?

 

[DPC]

Thought about that but I have ran modified pumps with stocker pumps in dual setups without issue.


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