Date: Thu, 7 Oct 2004 12:15:47 -0500
Reply-To: Stan Wilder <wilden1-1@SBCGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stan Wilder <wilden1-1@SBCGLOBAL.NET>
Subject: Re: VDO Fuel Pressure sender?
In-Reply-To: <b3a1e7ad04100709035cadb985@mail.gmail.com>
Content-Type: text/plain; charset="Windows-1252"
A vacuum gauge is a very handy gauge to use in a tune up procedure.
It is of course a standard item in many race and high performance cars.
I use a vacuum gauge between the distributor and Throttle body to check
vacuum while tuning my car.
The thing I most often note is that the vacuum gauge stabilizes as the cold
engine builds some heat. This indicates that the valves are seating
properly, the lifters are pumping up properly and generally I have tight
piston/ring fit.
For years I've run the following gauges on my Air Cooled engines; Oil
Temperature, Oil Pressure, Cylinder Head temperature on #3 Cylinder.
While tuning up and getting the engine to real world operating temperatures
I often pull as much as 27 inches vacuum.
You must consider that reading one of these gauges all the time is a waste
of time since you really can't control other events (other than slowing
down) by reading one.
The same thing goes for a fuel pressure gauge.
You can't change anything from the driver's seat relating to fuel pressure
unless you've got an adjustable fuel pressure regulator (very handy for Carb
engines).
With WBXers I'd say if you got a good oil pressure gauge and you monitor
your engine temps in degrees other than flashing warning lights that you're
controlling it about as much as you can or need to on a continuous basis.
I managed to run two Air Cooled engines a total of 225K with just simple
respect for engine and the readings they slowed or maintained at reasonable
speeds and load ranges.
There isn't any reason that you couldn't use a VDO oil pressure sender in
line to monitor your fuel pressure.
I'm not sure about monitoring the vacuum but I'm sure somebody makes an
electronic version.
Most VW Vanagon Cruise controls I've seen use a vacuum line from the engine
to the foot pedal for actuation of the cruise.
I've never been able to find any drop in vacuum from the twelve foot + 1/4"
hose run. That said, I'd guess that you could run a tube from the rear to
the front and have proper readings.
Stan Wilder
High Performance Ceramic Coatings
www.engineceramics.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Craig Oda
Sent: Thursday, October 07, 2004 11:04 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: VDO Fuel Pressure sender?
Max,
thank you for the information. This is helpful. I found three sites
that have a bunch of information on reading a vacuum gauge.
http://www.iwemalpg.com/Vacuum_gauge.htm
http://www.centuryperformance.com/vacuum.asp
http://www.fordf150.net/howto/diagnoseengine.php
I'm looking forward to putting the vacuum gauge tester onto my system
and telling me what it says. Per your setup, I'll probably put the
gauge inline with the vacuum line going into the fuel pressure
regulator. I suspect that my vacuum is low since I am getting fuel
pressure at 31psi instead of 29psi.
This is good timing for this bit of info. I was thinking of buying an
air compressor so that I could do a leak-down test on one of my
cylinders. However, I may not have to do this if I can use the vacuum
gauge to figure out if the misfire problem is due to leaking valves or
a problem with the piston rings...
I kind of like these gadgets that monitor the engine. I would like to
intall a permanent vacuum gauge. However, I'm leary about running a
vacuum line all the way from the engine compartment to the front of
the van. I would much rather have an electronic sender tapped into
the engine compartment. Though, I guess that this type of sender does
not exist.
Well, I'll do some tests with the mechanical gauge. Thanks.
Regards,
Craig
On Thu, 07 Oct 2004 01:27:50 -0500, Max Wellhouse <maxjoyce@ipa.net> wrote:
> Craig and Listees:
>
> You're plan on the fuel pressure mounting is pretty much what I had
> planned. I was being facetious about doubling up the vacuum gauge and the
> voltmeter. there is no sending unit for the vacuum gauge(at least not the
> VDO vacuum gauge). I originally used 1/4" soft copper tubing routed under
> the vehicle from the engine compartment to the place under the dash where
> the heater hoses come up through the body. I have since been told that
the
> diameter of that line is too big for maximum gauge accuracy, so I went
down
> to some really skinny black plastic tubing(maybe 1/8" or less) I bought at
> NAPA. It's about the same diameter as the extension hoses you get with
an
> air shock kit. I fished that inside the copper and have had no
> troubles. Tied the vacuum line into the fuel pressure regulator line with
> a small T connector and then used a plastic adapter to go from the small
> plastic hose up front to the threaded 90 degree end of the gauge. . I
> think regular vw fuel line braided cloth hose slipped over just fine with
a
> small hose clamp for security. The closer you tap vacuum to the intake
> manifold, the more accurate the information you will get( ie don't tap
into
> the vacuum line that goes to the charcoal canister)
>
> A vacuum gauge can accurately tell you many things about the health of
your
> engine ie. burnt valve, slow or retarded timing, weak valve springs, etc,
> but I put it on there to keep my lead foot from putting me into the poor
> house! My Boston Bob engine with mild cam on it idles at about 15" of Hg
> and the difference between driving right behind a semi trailer(of course I
> don't do that anymore) in a stiff headwind and regular driving with no
wind
> break REALLY shows up on the vacuum gaugeI don't think the VDO gauge came
> with the diagnostic details of what the vacuum gauge will and won't tell
> you, but Most of the old Clymer VW manuals for Rabbit and Dasher have an
> excellent troubleshooting guide. I also think buying a cheapo vacuum
gauge
> tester from an auto parts store(the big garish looking one) should have
the
> same info. Maybe that info is on line somewhere also. I was going to
use
> the water temp gauge sending unit from my Haltech engine management
system,
> but now I'll check it's resistance readings first. If I have to spring
for
> another VDO temp sender, I'll do it. Cutting one of the smaller coolant
> hose lines in the back of the engine won't be too much of a hassle. As
far
> as stringing the extra wires, I already have 4 in the loom, so adding 2
> more won't be too much of a hassle. The beauty of the vacuum gauge is
that
> the only wiring necessary is the wiring for the illumination. thanks for
> the reply.
>
> Max
>
>
>
> a 06:06 PM 10/6/2004, Craig Oda wrote:
> >I use a VDO pressure sender as my fuel pressure sender. I have it
> >permanently mounted in the engine compartment attached to the fuel
> >pressure testing tap. It works reliably for me. I like it because I
> >can at least rule out low fuel pressure as a source of the numerous
> >problems that affect drivability of my Westy. ;-)
> >
> >FYI, I was originally using a cheap JC Whitney oil pressure gauge and
> >it died on me after a few weeks. :-(( Worse, it was giving me
> >incorrect readings. :-(((( which made debugging the fuel system much
> >more difficult. I identified the problem by running a mechanical
> >gauge in parallel to the electronic sender and running repeated tests.
> >
> >The VDO pressure sender seems to be of a much higher quality.
> >
> >If you're going to run more wires under the van, you might want to
> >consider running a pre-built wiring loom, like the type the sell for
> >trailer lights. That way, you can run four wires at once at the wires
> >will be of different colors.
> >
> >What sender are you using to read your vacuum? Do they sell a VDO
> >sender for that? I'm intrigued.
> >
> >If you start putting different senders onto different gauges just be
> >aware that there are different types of senders. I think that the VDO
> >pressure senders are 0-180 ohms and that needs to match up to the
> >proper gauge.
> >
> >Let me know about the vacuum gauge. I've got two spare wires running
> >from my engine compartment to my dash that I could tap into.
> >
> >Also, does this really help with isolating vacuum leaks? I always
> >suspect I have vacuum leaks, but never went through the hassle of
> >attaching a vacuum gauge. I've got a mechanical vacuum gauge tucked
> >away someplace in the garage.
> >
> >-- Craig
> >
> >
> >On Wed, 6 Oct 2004 17:46:41 -0500, Max Wellhouse <maxjoyce@ipa.net>
wrote:
> > > Can I use my spare VDO oil pressure sender as a fuel pressure sending
> > > unit? I have used it for this purpose once to check FP
diagnostically, but
> > > was wondering if it was okay for long term use? I was going to run
two
> > > extra wires from the engine compartment up to my 3 gauge pod on top of
the
> > > instrument cluster(op/vacuum, and oil temp).
> > >
> > > By rigging up two toggle or rocker switches nearby, I was going to
have the
> > > pressure gauge where I could read either oil or fuel pressure and then
have
> > > the temp gauge do both water and oil. Now if I can just get a toggle
> > > switch to make the vacuum gauge read volts(yes, I'm taking that too
far).
> > >
> > > thanks
> > >
> > > Max
> > >
>
>
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.772 / Virus Database: 519 - Release Date: 10/1/2004
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.772 / Virus Database: 519 - Release Date: 10/1/2004
| 
