LML Help??? Lml P0087 Reprogram flow rate?

[TxDmax88]

We went through am issue with a bad cp4 fuel pump. Replacing everything.... and I mean everything. Anything the fuel touches needs to replaced. We flushed complete fuel tank including sending unit in tank fuel lines to engine and return lines from engine. All hard and soft lines on engine. We had the fuel rails cleaned with a special sonic or something cleaning machine. Also had all hard lines done we replaced injectors and fuel filter including fuel filter assembly. We still ended up having a loss of power issue over 2300 rpm. No codes tho. Ended the only thing we didn't clean was the injector return lines on engine that head back to tank. The injector return lines from each side of engine y together through a regulator. The lml injectors will not function properly without the right back pressure, hence this regulator, ended up replacing that part and the truck finally ran good. We did have efi live tuning and motor ops helping with tuning issues also.

The return line regulator that you replaced, is it located on the top of the cp4? That may be my problem I didn’t think about replacing that.
How was your mileage before and after? I’m getting poor mileage (13mpg) yet ok Preformance out of a 100 hp tune.

 

[ikeG]

The AC Delco 'pump kit' part # 12672028 comes with 8 injectors, 1 cp4, and both rails, including the rail pressure sensor and regulator, is what gm dealers use to fix these trucks. I pay only $1700 per kit. Individually, these items cost $3500 my cost at the dealer. I think they have this kit marked down in order to make their warranty repairs look better. Definitely the way to go financially. Unless you understandably want rid of the cp4. I currently have 3 here to do.