Ok, on the passanger side of the fuel rail, there is a fuel pressure check valve. I have no cap for the valve and upon inspection I see its just a hole. Is there supposed to be a valve core or needle valve of some sort in it? Where can I get a cap for it also??

 

You might try GM Parts Direct: Your direct source for Genuine GM Parts web site.
Also, find a AC Delco dealer in your home town and be very nice to him when you go in, and they might be able to order it for you. I've gotten connectors, memcals, speedo sensors, and gears from the AC Delco dealer in chattanooga. The dealer will just tell you, Not Available.

 

The valve core, seal, and cap are sold as a kit. The part number is GM# 17110854. At GMPartsDirect, the shipped price is about $31.

If your fuel rail is on a running engine, I would assume that the schrader valve is intact. There must be a core that you are not seeing.

 

Thanks guys, I'll look to see I can remove the valve on the rail now and inspect it closer. Upon looking down on top of it I don't see any kind of needle or core, I don't have a cap either. Can I install a permanent Fuel Pressure Gauge on this port?