HP 500 EFI, Fuel Pressure - Schrader Valve?
 

I assume you do not need to remove the plenum to access the schrader valve on the fuel rail to test the pressure, do you?

I looked for it the other day, quickly, and didn't see any schrader valve visible, I looked where its supposed to be based on the parts drawing but couldn't see anything.

can someone please confirm location and that you can test without removal of the plenum.

Thanks.

It's on the r/h side of the engine between the runners,
probably closer to the rear than the front.

http://www.mercruiserparts.com/Show_...+And+Injectors

item # 4 in the pic.

You can get to it without removing the plenum, you may have to wiggle the wire harness around to gan access to the cap.