Cp3 failing??

[Jesse2006duramax]

I have an 06 lbz stock fuel, within the past few months I began to notice at half throttle the fuel rail pressure would bounce. WOT it smoothed out and fueled fine, sent my tuner a data log and they sent new tunes to try to work it out and that didn't fix it. Now it's started to lose rail pressure at work. It'll drop below 20kpsi. I do have a lift pump and u just replaced filters a few weeks ago, right before a cold wave. And ideas from anyone as to what could be or what to check?? Thanks in advance

 

[IOWA LLY]

I had a customer request a new CP3 for this very concern. I told him it could also be the injectors. But he wanted to start with the pump. It helped it tremendously, but still does it ever so slightly. However, he opted for a 10mm pump, so it could be that the pump is simply able to overcome the worn injectors.

I feel that injectors alone would have fixed it. But I can’t answer 100%.


Sent from my iPhone using Tapatalk Pro

 

[Jesse2006duramax]

Oh really? I guess leaking by into the return?

 

[IOWA LLY]

Yes. High return rates.


Sent from my iPhone using Tapatalk Pro

 

[Ne-max]

We have been seeing many lbzs around the 250k mark needing injectors.

 

[2004LB7]

Do an injector return rate test. That will tell you if you need injectors or a pump

 

[Jesse2006duramax]

How do I go about doing so? And truck only has 120k miles, but it has been pretty rough on the stock fuel with the larger turbo on it

 

[Dozerboy]

There are posts talking about it. To do it the right way you need to by a test kit. Basicly you pull the fuel return lines off each injector start the truck and let it run for a certain amount of time. When you shut it off and you measure how much fuel you captured out of each injector return line. When I did mine I just tested each Bank of injectors as a group. It's not as accurate but generally if you have an injector or more bad it's a pretty significant amount of fuel that it'll be returning. You had one bank that returned a lot of fuel he would still need to test each injectors individually to find out which one was bad. I want to think you can find the kit for like 80 bucks

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Jesse2006duramax]

There are posts talking about it. To do it the right way you need to by a test kit. Basicly you pull the fuel return lines off each injector start the truck and let it run for a certain amount of time. When you shut it off and you measure how much fuel you captured out of each injector return line. When I did mine I just tested each Bank of injectors as a group. It's not as accurate but generally if you have an injector or more bad it's a pretty significant amount of fuel that it'll be returning. You had one bank that returned a lot of fuel he would still need to test each injectors individually to find out which one was bad. I want to think you can find the kit for like 80 bucks

Sent from my SAMSUNG-SM-G900A using Tapatalk

Okay thank you

 

[Dozerboy]

I guess I forgot to say. The reason I tested each Bank of injectors is I didn't need to buy the test kit. You can just unhook the return line on each Bank and use the stock setup.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Ne-max]

I guess I forgot to say. The reason I tested each Bank of injectors is I didn't need to buy the test kit. You can just unhook the return line on each Bank and use the stock setup.

Sent from my SAMSUNG-SM-G900A using Tapatalk

Works well. If loosing rail that bad it's usually multiple injectors going out anyways

 

[Dozerboy]

Excellent point

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[ikeG]

I've done a few @ 200k. Solved the low rail issue and the cp3s were still strong as an ox. Anymore, I don't even waste the money to have them tested if it's the right circumstances. Just get all 8

 

[Brent@LDS]

We see this issue all the time here. Injectors with high return like stated above.