Your mechanic theory about only needing lift pumps if you go over 700hp, is ridiculous.
I’d seriously consider finding another mechanic.
I have a AirDog 100 LP with adding about 40hp, probably didn’t ’t really need it but lift pumps provide positive fuel pressure, which makes it easier on the stock fuel system.
Having a LML with the cp-4 this should/might help from having future fueling issues.
Search and read up on problems with the CP4 vs CP3, it’s very costly converting over to
the CP3, that’s what most LML owners have said they are doing.
Adding more than about 80 hp with out a lift pump you’ll eventually have fueling issues.
Changing the fuel filter is probably a good idea to start, adding a liftpump would be even a better idea.
2007.5 GMC "Black" Sierra SLT 3500HD SRW C.C. 4X4 LMM Z71
DIY stock airbox mod, aFe ProGuard 7, OEM drop-in
EFILive ECM ATP - Heavy Tow Tune with Turbo Brake
EFILive TCM Duramax Tuner
DHD Cold Side High Flow Intake Pipe
DHD PCV Re-route
2007 GMC Yukon Denali "BLACK" 6.2 gasser, DIY stock airbox mod, K & N OEM drop-in, Airaid intake tube, EFILive TCM tuned
Last edited by D_R_C; 04-28-2019 at 08:23 AM.