LB7: Air coming from return line cp3

Justmikedmax

New member
Dec 26, 2016
18
0
1
Clermont FL.
So as the title states I’ve got a good amount of air bubbles coming from cp3 return . I replaced all supply lines with clear ones from tank to ficm ,to filter head . With no bubbles so I just installed a line from cp3 return to return block and have a strong amount of air bubble coming from cp3 .. Bad cp3 ???? New injectors ,fpr,hard lines ,lift pump ect. Been chasing a strong power loss but rail pressure follows real close from actual to demanded all the way to 23k but truck is lacking in power . Maybe cause cp3 is pushing air into injectors ??any knowledge or help would be greatly appreciated
 

2004LB7

Well-known member
Dec 15, 2010
2,656
26
48
Norcal
Maybe the seals or O rings on the gear pump on the back of the cp3. Or the hose connection right at the cp3
 

Justmikedmax

New member
Dec 26, 2016
18
0
1
Clermont FL.
Yes running a 150 . That’s why I think it’s still running ,also just now pulled power to lift pump so truck running on cp3 suction . Idle and throttle up fine ,but when I unplug the fuel rail pressure sensor truck dies, with lift pump running and I unplug it will and out rail pressure
 

Redkliney

New member
Apr 10, 2020
7
0
0
Pa
Ever figure this out? I just replaced my injectors and cp3. Ran great for three days. Gave it the flat foot for the first time going around a corner and truck dies. Ever since then i have to reprime it for every start. Litteraly ever start. Shut it off wait a few seconds, needs reprimed. Put all clear lines on filter head to cp3 then decided cp3 return. No air in but a good bit is coming out the return. I know this thread is old but im stumped.
 

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