[Vwdiesel] 93 EV DSL fuel filter Q

[James Hansen]

plastic thing is a thermal controlled valve- puts warm return fuel to the
filter when cold to keep the filter from plugging with solidified fuel in
winter.

ELectrical tape plugging the valve off.  You pretty much have it there, that
would not be a seal worthy of a fuel system.

Pump is not really designed to push anything through the return side, its a
pretty passive setup, not designed for backpressure to any extent.

The filter routing is as stated, for cold weather supplemental fuel heat-
the warm fuel from the IP goes back to the filter, having nothing to do with
making it easier to suck fuel...   They run just fine with the return going
back to the tank, that's the way the early stuff (A1's) were routed.
-James

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com]On
Behalf Of rOLf peCHUkas
Sent: Friday, March 10, 2006 10:06 AM
To: vwdiesel at vwfans.com; ev_update at yahoogroups.com
Subject: [Vwdiesel] 93 EV DSL fuel filter Q


hey all
I have a '93 EuroVan Diesel running on vegetable oil
yesterday I did some fuel line re-routing that screwed things up when
I'm running on diesel and I want to understand why
the fuel filter on the DSL (maybe the gas too) has regular in/out
ports for lines from the tank and to the engine
but it also has a little plastic valve cap thing that the return line
from the injection pump runs through on its way back to the tank
I re-routed to DSL return yesterday to backflush the veggie filter
when I'm running on DSL
and capped the barbed fittings on the little plastic thing (temporary
work to see if it would function - just capped the ends with
electrical tape)
and temporarily left the return line to the tank un-terminated - just
open to the air
now when running on DSL IP (injection pump) is fuel-starved
runs OK on DSL at idle but on the road it dies
runs fine on veggie
I'm guessing that under load IP is working harder/pulling more
strongly and may be sucking air through the electrical tape on the
filter return cap
DSL line is indeed filled with air
but my question is:
IF the plastic thing is capped tightly
SHOULD the IP be able to pull DSL from the tank (and push return
backwards through the veggie filter)?
or is it important for return to be routed through the filter so that
IP can pull from the return line in a loop (this would presumably
make things a lot easier in the IP)?
does anyone know if that plastic return fitting is designed to remove
air from the return line or allow loop flow or both (or something else)?
but the basic question is: can the VW IP function properly with the
DSL return going someplace other than through the fuel filter
?
thanks for any insight
--
Rolf Pechukas
Cambridge, MA




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