Date: Sun, 20 May 2012 22:21:29 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Use Air Cooled Fuel Pressure Regulator on WBX?
In-Reply-To: <CAB2RwfhO7LfChb0reyw0HKx47OGOSeU5n1GN=oNDOLZWSxqNCQ@mail.gmail.com>
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Why do you think you may need to replace the fuel pressure regulator? They
are easily tested and almost always a failure is obvious. The typical
failure is the diaphragm which becomes obvious as the intake manifold gets
filled with fuel or the shell gets rusted it leaks on the outside. If it is
a case of low fuel pressure the regulator can be tested by crimping the
return hose. If this raises the pressure to the required pressure then the
regulator is leaking by.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
neil n
Sent: Sunday, May 20, 2012 11:31 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Use Air Cooled Fuel Pressure Regulator on WBX?
Cool. Thanks David.
My gut told me that there might be some issue with both return lines pushing
fuel into one inlet. But as you suggest, I could measure pressure.
Thanks for explaining.
A brass " T " isn't available at my FLAPS, but it does exist of course and
is what I would've used.
The FPR bracket is easy to bend but maybe only to 45º maximum. Hose routing
to accommodate the single inlet type FPR might be difficult. e.g. I found
that even "just" moving fuel rail hoses to top of intake, and feed/return
hoses over to driver side of firewall presents a challenge. (where will it
chaff, wires nearby etc.) A single inlet FPR, with FPR bracket bent to max.,
at best, (in my minds eye) would still put the return hoses at an awkward
angle. The feed hoses to new " T " would need to be curved thus routing them
over parts.
So theoretically possible but hose routing might make the idea moot? I
don't feel like spending more money on a test part but could mock something
up I guess.
Neil.
On Sun, May 20, 2012 at 12:26 AM, David Beierl <dbeierl@attglobal.net>wrote:
> At 02:10 AM 5/20/2012, neil n wrote:
>
>> A " T " would be required at inlet, there would be 2 more hose clamps
>> than with the WBX part, positioning it might be a problem, but other
>> than that, will the part work correctly?
>>
>
> I haven't done it, Neil, but I don't see any likely issues. The AFC
> fuel pump delivery rate is the same, injection pressures same, the
> venting rate back to the tank should be the same or less. The AFC
> system appears to feed at one end of the system and vent at the other;
> the later ones feed at both ends and vent in the middle (or to say
> another way, feed the two sides of the engine in parallel) which gives
> both sides the same inlet fuel temperature. Doing it that way it
> becomes more convenient to have two input nipples on the regulator.
> The only possible (not likely) issue I see with using a tee is
> turbulence/noise/restriction where the two flows are constricted,
> meet, and abruptly turn 90 degrees at the tee instead of feeding into the
less constricted turning point inside the regulator.
> Since the fuel pump is a positive-displacement type with excess
> capacity it's not going to cause *it* a problem, and I find it hard to
> believe it would constrict flow enough to cause a problem with pressure
regulation.
> If you're anal you could test this by installing a tee in place of
> the existing regulator and measuring pressure at the test tee (not the
> one you
> installed) while running the pump with a jumper. If you wanted to be
> even more persnickety you could then measure the same pressure
> downstream (toward the tank) of the new tee and subtract it from the
> other reading to get the true max pressure drop across the tee itself at
max flow
> conditions. We're talking about half a liter per minute flow rates here
> at 35 psi net pressure drop in the system and gasoline's not very
> viscous, so I really don't see a problem. The tee would have to be
> fuel and temperature safe at pressure, of course, and if the return
> line somehow got pinched it might see over 100 psi. A metal tee would
> take care of any worries there.
>
> Yours,
> David
>
--
Neil n
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