Re:Pressure relief valve, et al.

[John Larson <jdlarson@ix.netcom.com>]

Regarding the ill running 89 100, remember that , at least on the 85
thru 88 cars, there is a fuse along the side of the fusebox which tends
to be confused with a spare. On the 87 5kq that`s here, it`s position
27, a 15A fuse. Lotta  people tripped up by this one, and it has to be
there. Before I went any farther, I`d unplug the O2 sensor, and run the
car. It`s an easy test.
They use  a regulator very similar to this one on the CIS-E VWs and I
can`t remember a bad one. We see bad ones off & on on the Digifant cars,

Fords and once on an Eagle, all electronic injection cars.  Sometimes
they leak through the vacuum hose into the manifold, sometimes they go
way overpressure. If you suspect the reg., disable the spark, remove the

outlet line, put a hose over the end, and crank it. You should get a
pretty good flow. Put the line back on, fix the spark, run it. pull the
vent  line, see if gasoline comes out. From the 90 book, this appears
to  go to the air filter housing. As I said, I`m not familiar with the
specifics of the 89, but the principles are always the same. Remember,
if it`s too lean, the backfiring  is typically through the intake, too
rich, through the exhaust. Remember, too, that this a pretty
sophisticated system, and you`ll have better luck diagnosing the system
if you understand what the various components are and what they do. A
typical parts guy is probably  not the 1st person  to ask. If you don`t
have a Bentley, or access to some other GOOD manual, this could get
financially hairy, real quick. Lacking a manual for a particular system,

or one awfully similar, even with 25 years experience, I`m  reluctant to

dive in to something like this.If you want to bounce more ideas off me,
e-mail me off list, I`d be glad to do what I can to help you.John
Larson. <jlarson@ix.netcom.com>