2015 LML CP4 questions


New member
Sep 13, 2020
Asking about Bosch CP4 vs AC Delco CP4 fuel pump. I know some reviews say the cp4 pumps are junk. Doing some checking on what to do. I have a 2015 Duramax LML with 94K currently on the engine. I am second owner its been deleted and as far as I can tell nothing else has been changed. Wanting to understand if replacing cp4 would be a good thing and I am seeing new improved cp4 pumps. Or should I do a cp3 swap.


Well-known member
Dec 15, 2010
Welcome to the site

The rate the CP4s fail is not thay high to "need" to replace it right away. I would do a CP3 conversation if your CP3 starts to have issues. Otherwise I would leave it be and always fill up from a high volume station and maybe even use a diesel lubricant additive if you want

Is far as I know, there are no versions of the CP4 that have solved the issues with them

diesel vein

New member
Apr 2, 2011
I just put in a cp3 conversion in a 11 that I had put a new cp4 in 4 years/130k ago. I will likely never reccomend replacing with cp4 again. I'm seeing them failing from 120-150k the most.

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