RIP lml cp4

[Tater1]

Driving down road today and truck dies instantly. Luckily I was close to home. Hooked scanner up and no rail pressure. So I guess cp4 has died. 130k miles. Just deleted emissions a month ago with a h&s tuner. Anyway considering doing the injectors, pump, rails, lines, lift pump myself. I have the capabilities and resources to tackle it.... I think. Any advice? Horror stories?
Thanks

 

[coker6365]

Check your factory fuel filter and make sure you do not have a leak first. I had one of my 2013's die leaving the driveway. V2 showed no rail. Hit the primer button and found the filter leaking around the oring.

Sent from my SM-G930V using Tapatalk

 

[Tater1]

Hey thanks. Forgot to mention it's a 2012. And I replaced the whole filter base /pump assembly. No luck.

 

[FC5452]

You can clean the rails and high pressure lines, fuel supply and return line to the tank.
Drop tank, flush it out for any debris in it.
You’ll have to buy and replace the injector return assembly as well.
Check for debris on the regulator before going and tearing it all apart, unless you are going to do a swap anyways.

Job isn’t all that hard, it’s harder deciding what size pump and sticks you want to run


Sent from my iPhone using Tapatalk Pro

 

[Tater1]

So if I pull regulator and it's clean? Then what? Gonna pull it in the morning.

 

[FC5452]

Check the wire harness for frays and or rub throughs. Prone at the ecm where the harness is next to the frame, over and behind the ac and alt areas as well.



Sent from my iPhone using Tapatalk Pro

 

[Tater1]

Which regulator should I pull? I understand there's one on top of the pump and one on the fuel rail? I really appreciate the help

 

[FC5452]

If you have the egr out reach in and pull the pump.
The one on the rail after you confirm metal debris on the pump, that would give you an idea how far the metal traveled.
I don’t want to be the bearer of worse news, but if your going to swap the IP for a cp3 you’ll have to invest in efi or EzLynk as a tuning platform.


Sent from my iPhone using Tapatalk Pro

 

[Ne-max]

Buy the LML cp4 fail kit. Comes with 8 injectors,cp4 and both rails. I personally would replace all high pressure lines and return lines. At 28000 psi metal can get stuck to the lines. Would not risk it over what it cost.

 

[AZlml]

I wouldn't put another cp4 in it especially since you'll have the whole thing apart. Peace of mind knowing you won't be doing it again is worth the cp3 conversion.

 

[Tater1]

Took it to a local shop. He says there is no rail pressure cranking. Unplugs the regulator and it goes to 31k psi. How does it make that much pressure if the pumps bad?

 

[DAVe3283]

Did they unplug the regulator, or the sensor?

If the rail went up to 31k, it would start. I'm guessing they unplugged the sensor.

 

[Chevy1925]

what are the codes. ill bet there are a few

 

[wilsondiesel]

I have one that's tripped a p0087 and when logging rail psi at wot, desired is 29k but actual around 24-25k, this truck only has 78k miles, it is deleted and running an Air Dog, time for a cp3 conversion?

 

[Chevy1925]

I have one that's tripped a p0087 and when logging rail psi at wot, desired is 29k but actual around 24-25k, this truck only has 78k miles, it is deleted and running an Air Dog, time for a cp3 conversion?

how big is the tune?

 

[wilsondiesel]

how big is the tune?

Just an economy tune.

 

[Brent@LDS]

If you end up needing the pump/injectors and rails we have a full kit here at a killer price! Let me know if i can help.

 

[FC5452]

I have one that's tripped a p0087 and when logging rail psi at wot, desired is 29k but actual around 24-25k, this truck only has 78k miles, it is deleted and running an Air Dog, time for a cp3 conversion?

Have you checked the regulator on the fuel rail for debris ? Any type of debris will fail the regulator and cause it to stay open longer than required tripping the code for low fuel pressure.

Then there’s the basics with the rubber on the fuel supply lines, and the fuel basket in the tank collecting garbage in the screen.

If you find debris on the regulator, you can assume the worse with the cp4.


Sent from my iPhone using Tapatalk Pro

 

[Chevy1925]

Just an economy tune.

has it done it since the tune? there are a couple things that must be done right in the tune to keep rail pressure up.

 

[wilsondiesel]

has it done it since the tune? there are a couple things that must be done right in the tune to keep rail pressure up.

Believe truck felt a little sluggish before delete, but its only coded once for low rail in the last 7 months since its been deleted.