Where is the schrader valve located on 1998 grand prix se?
...everyone should have a manual for their vehicle(parts store or dealer), and a local library should have professional shop manuals available in the REFERENCE section for free...make copies of the appropriate sections...read up and good luck :)
My first guess would be to use the Schrader valve on the fuel rail as the connection point. From the front of the car, the fuel rail should be just behind the valve cover, and it should be rather shiny. On the left side of the fuel rail, there is a Schrader valve (like the valves on the tires), and this is where you can connect a fuel pressure gauge.
If it's like my 1995 4.0 L OHV , I believe the schrader valve for checking your fuel pressure can be seen looking from the passenger side of the engine . It is on the fuel rail , which is installed between your lower and upper intake manifold sections , about the center of the fuel rail I concur. This is the same location as on my 1998 4.0L OHV.