I just rebuilt my 3.8 in 87 GN. Got things back together and fired it up. Things are looking really good. Even scanmaster numbers are looking good after some driving and testing and adjustments. I did notice that it was burning an incredible amount of fuel even though scanmaster numbers didn't indicate a fuel problem, and driving seemed nearly perfect, lots of good power, no stumbles or misses, turbo and boost worked fine.....even better than before I rebuilt everything. I decided to check fuel pressure and do some adjusting if necessary to possibly address fuel consumption issue. I connected fuel pressure gauge and turned on the ignition without starting the engine. I checked the gauge and the first thing I notice is a after the fuel pump shuts off the pressure starts to drop, and pretty fast too. I would say it takes about 30 seconds for the pressure to drop from 40 to 20 psi. And after some checking and re-checking with no change, i notice that as the pressure drops, the slower it drops as the pressure goes down. I have a racetronix 255 fuel pump with hotwire kit installed, Adjustable fuel pressure regulator, turbo tweak 5.7 chip with 42lb injectors to match chip. I've had that combo for about 4 years and never had an issue, always good fuel economy. I tried adjusting fuel pressure, with the regulator backed all the way off, I can't get it to go below 40 psi with vacuum line off, (I know it should be set to about 43psi with vacuum line off, but I was playing with the regulator to make sure it's working properly), I can raise up to 60 psi plus no problem (could go more but I didn't try going any high than that). I put new o-rings on the injectors when I installed after the rebuild. So I'm thinking that the fuel pressure drop with engine off could just be a leaky check valve on the pump, but I'm also thinking that the pressure regulator doesn't seem to be acting right, and I'm also thinking about the incredibly poor fuel economy. There is no external fuel leaks anywhere. So do I have leaking fuel injectors......bad pressure regulator......combination of both? And with the excess fuel consumption, why doesn't the numbers on the scanmaster indicate it? I need some advice.