This much I know: the vacuum line that connects to the fuel pressure
regulator (Quad 4) has broken.
I don't know where the other end of the vacuum line attaches. When I
found the leak, the vacuum line was laying on top of the intake
manifold about six or eights inches from the fuel pressure regulator.
I have the replacement vacuum line, but I can't find the nipple(?) on
the intake. My Haynes manual has a picture of the entire engine
compartment and I see the vacuum line I'm working on, but that Quad 4
is slightly different from mine. That picture shows a nipple close to
the nipple the MAP sensor uses, but my Quad 4 does not connect there.
I have ordered a Chilton manual, which is supposed to have a vacuum
diagram, but it may not arrive for two weeks. Can someone tell me
exactly where the line attaches? I would greatly appreciate it. I'm
sure I'm over looking it.

Thanks,
ATL

I found it on my own, but in case anyone happens to have the same
problem someday and stumbles upon this thread...The nipple for the fuel
pressure regulator vacuum line on a 1990 Pontiac Grand Am Quad4 is
located on the inside (toward the firewall) in the middle of the intake
manifold. The nipple directly faces the engine. From the top, it is
to the passenger side of the MAP sensor. You can see it if you look
directly down b/n the two middle intake portals(?). To access it, you
will have to put your hand under the intake manifold while looking from
the top. I got the line started by using pliers to hold the line and
wetted the nipple.

Hope this helps someone else someday.

ATL