I bought an EFI set up from a guy, it is the style that uses the fuel pump on the block. My question is that on the front underside of the plenum(over top the thermostat) there is an open hole(threaded), is there supposed to be something there, or do I just put a plug in it.
Thanks Steve

The fuel pressure regulator has a small hose on it, and needs to pull vacuum from the underside of the plenum. there are a couple spots on the underside that you can unthread a plug and thread in a barb. maybe the guy just took the barb out.

Are you talking about the hole for #46 in this illustration:
http://www.mercruiserparts.com/Show_...+INTAKE+PLENUM

If you're using PCV then you need that 90 deg fitting, if not, you can plug it.

Ok, I bet that is what it was for, looks to be in the right place. If I chose to run a PVC, would I run it in the valve cover, like the cars do. What about the other valve cover opening, put a breather in it? Steve

#31

http://www.mercruiserparts.com/Show_...D+ROCKER+COVER

Thanks, That's what I thought.
Steve