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You're not going to like the answer... but the Fuel Pressure Regulator is attached to the Fuel Metering body opposite the fuel lines. Meaning its INSIDE the intake. And to get to the fuel metering body requires removing the upper radiator hose and intake and all those little annoying hoses and bolts to boot.
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Warning: User exhibits tendency to use offensive amount of smileys... 2003 GMC Denali XL
LQ9 | LS2 Timing Chain | LS6 PCV System | HPTuners MVPI Pro | 1 Bar Speed Density OS | Dual LC-1 Widebands | MAF Deleted | ASM Long-Tubes | Self-Built 4L65E | Yank Pro-Truck 3200 | Corsa Sport Exhaust | SSBC Truck-Force 10 Calipers
All the Gen-Ie Vortec engine had CPI or SCPI injection. The fuel goes into a central assembly where all 6 or 8 injectors are housed. From there the injectors feed individual tubes with poppet valves on the ends to each port. The biggest proplem is that the poppet valves have proven to be incompatible with certain fuel additives and can stick open or closed. GM's resolution was to release a retro-fit assembly that has individual tiny multec-II injectors at the ends of the spider tubes. This is a vast improvement but still limited and non-upgradable in flow.
The injection in these engines has always been the single limiting factor in making big power. (Look at all the trash inside air has to get around. Combined with the weak valvesprings it's no wonder they don't breath past 4800RPM!)
I only just recently rid my truck of the SCPI disaster:
Now running 36# injectors instead of stuck with 19#.
I could suggest replacing the whole thing with the upgrade unit.
Part Number 93441235.
It includes the complete assembly, 8 injectors, new regulator, new o-rings, and is ready to install. These things are not very expensive and will help the truck pass emission and idle smoother.
Those of us who have done it have found it necessary to shim the support bracket to bring the assembly to the proper height. Also, lube the o-ring seal around the unit and the inside of the upper manifold with grease to help get the top back on. It's tight.