I recently swapped my '72 GMC C15 over to a 2005 5.3l LM7 motor and a 4l80e trans. I am using an '02 Camaro SS fuel tank/regulator with one feed to my return-less rail, and a loop off the feed line back to the regulator on the fuel tank assembly. I am getting 58-60lbs of fuel pressure consistently so the regulator seems to be working.
My issue is that I am tuning VE and seeing 40% LTFTs?!?! I've only changed to a CAI and a 450 Walbro. I compared the tunes from the '03 Suburban and the '05 LM7 tunes and no difference.
I also looked for vac leaks using smoke and propane but, could not isolate any leaks, much less one that would skew me to 40% LTFTs.
First ever swap/tune so, could use some guidance, please!