My blazer throws random miss codes but I don't think it is an ignition problem. With engine running it's close to 62psi. as soon as I shut down it drops back to zero within a minute or 2. Installed new fuel filter and a shut off in the supply line and it pumps to 75psi and holds. I installed the shutoff in the 5/16' return line and build pressure but I don't see 75psi at the test port and the pressure drops back to zero in short order. It will just barely start but I don't see any black smoke like the was a bunch of fuel laying in the intake manifold. I could not see any washed out ares when I removed the throttle body and could see no obvious leaks when I pressurized the system. Engine runs ok after it starts, it has a lot of power when you first take off then gets weaker after running for a while. Is there any chance it is a bad pressure regulator? How can I find what's causing the pressure loss? I've read the sticky over and over.

 

Ok, ok so you guys saw the Mustang in the driveway next to the blazer and yes I am an invader from the Mach1 registry. Yes but my son and I have two Blazers (94 & 97) and a 3500 Express van so GM and Blazer live at our house. We are a blended family that likes our wheels!
My question probably should have been; is there any chance it's just the pressure regulator? My old fart logic thought if it was bypassing down the return it would build pressure when I plugged the return. I have zero experience with this type of fuel injection under the upper plenum, and how do the poppet valves open? Is that another name for injector I'm corn fused, and scared of having to replace that whole spider assy. I've seen some of the prices on line and we're just not to flush with green here. That's our situation. Plus I need to post more so I can ditch the ads and spend some money in your classifieds. My son needs to work out of the Blazer so we can park the Express and slow the bleeding at the pump. I may be old and fat , but I can go on a diet, that fuel injection will be ugly forever!