Hi,

I have one of these vacuum guages and I have borrowed Robert Lilley's fuel
pressure guage, so I will give your test a try next week.  I measured it
last weekend at 32 psi unconnected and 39 psi connected -- slightly too
high but not enough to worry about, I hope.  I forgot to plug the manifold
vacuum hose, though, so I need to repeat this measurement.  (What does the
g stand for in psig?)

While attempting to evacuate my AC system, I noticed the MV as 10" to 12"
Hg just as you state.  Do you think I have a leak somewhere -- I hadn't
thought that it might should be 15".

Thanks,
Michael Townsend
90 Carat
Durham NC

PS.  Finally got my R-134a charged this morning -- looking forward to a
cool drive home!

> The problem with this spec. is that we don't know (okay, I don't
> know--maybe you do) what idle MV is for this spec.  As MV decreases, the
> fuel pressure at the tee will increase.  In other words, if you have an
MV
> leak and perform this test, you'll measure something higher than 28 psig
> for the hose connected test, even if your FPR is mechanically sound.
>
> Frank Grunthaner suggested that the 10 to 12" of vacuum many of us
consider
> "normal" for our wasserboxers seems too low and that at least 15" is more
> typical for modern gasoline engines.
>
> Sooo... I performed an experiment to find out what the test tee fuel
> pressure would be if my manifold vacuum was 15".  I did this by
> disconnecting the FPR vacuum hose and plugging it.  Then I connected my
> MityVac brake bleeder/vacuum diagnosis tool.  This tool is a simple
> hand-actuated vacuum pump that can pull up to 30" of vacuum.  It can also
> function as a simple vacuum gauge.  (The vacuum gauge on this new tool
has
> a stated accuracy of 2-3% but I cannot guarantee its calibration. )  I
> measured 28 psig at the fuel line test tee with 15" vacuum pulling on the
> FPR.
>
> Scott Terry
> '85 1.9L Westy "Pearl"
> Santa Barbara, CA
> Still parking next to other Westys despite the danger...