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Mk1 [tech] - Addition of pre-pump?
You can't fit the transfer pump into the early style
gas tanks.
The full-size-spare-tire gas tanks have a baffle
riveted to the bottom skin directly below the cap. The
transfer pump will interfere with this baffle.
You can't fit the space-saver-spare-tire gas tank to
an earlier car (at least not easily) because the
mouting system is different.
I have heard of someone who had some success at using
a crowbar to break the baffle loose from its rivets in
the early style tank. Then you can push it out of the
way and install a transfer pump. Of course you will
have to plug the fuel lines on the outside of the
tank. As Drew mentioned, the tanks are shaped
differently, so I don't know if the transfer pump will
pick up off the bottom of the tank properly. You will
also have this plastic/metal assembly floating around
in the tank, which may cause it's own issues...you're
kind of on your own if you go that route!
What is the goal here?
The stock tank will starve on 1/4 tank or less. If you
can't get that low, your tank's baffle feed line (a
little rubber line between the baffle in the middle
and the pump feed on the side) has deteriorated and
you should rebuild the tank anyway. If you rebuild it,
have them put fuel cell foam in there to keep the fuel
from sloshing, and maybe have them fabricate a better
baffle. Just remember, "money is speed!"
But though they are a little better, even the later
style tanks will starve at low fuel levels. I don't
know if adding a transfer pump would improve the
situation enough to make it worthwhile.
Finally, all of these issues and solutions are illegal
for most forms of racing that require a stock tank. If
a stock tank isn't required, just get a damn fuel cell
and skip the whole mess completely!
Neal
--- Benjamin Harder <vwtype53@yahoo.com> wrote:
> Thanks Drew
> This does help... I think I will start by getting
> ahold of
> a transfer pump assembly and test-fitting it to the
> tank in my 80.
> Then the feed and return lines will need to be
> routed. I suspect
> this won't be too big of an issue.
>
> Thanks for the help,
>
> Ben
>
>
> --- Drew MacPherson <drew@scirocco.cs.uoguelph.ca>
> wrote:
> >
> > The biggest issue to resolve will be if the later
> style sender (with
> > transfer pump) uses the same tank fitting as the
> earlier style sender
> > only.
> >
> > I expect that this is the case. The next
> challenge will be fitting the
> > transfer pump into the tank. The 84.5+ cars have
> a slightly larger tank
> > with a small dish at the bottom where the strainer
> for the transfer pump
> > collects fuel from. IIRC the transfer pump
> assembly on the sender is
> > spring loaded to ensure that it sits on the bottom
> of the tank (I know
> > this to be the case with A2 transfer pumps, but
> it's been a few years
> > since I replaced the one on the scirocco.) It may
> be necessary to modify
> > the transfer pump or the line that connects it to
> the sender in order to
> > allow the pump pickup to sit at the bottom of the
> tank. Also, a number of
> > pre-84 A1 tanks I have been into have baffles in
> the tank around the
> > pickup tube (which runs out the bottom front
> corner of the tank) It may
> > be necessary to find an aftermarket tank (without
> these baffles) or remove
> > them (not sure if this is possible without
> destroying the tank.) The key
> > is to ensure that the pickup strainer sits as
> close to the bottom at the
> > lowest part of the tank.
> >
> > You will also need to block off your current feed
> and return connections
> > on the tank and re-plumb your fuel lines so that
> the transfer pump routes
> > to the main pump (good idea to put in a small
> resevoir or later Scirocco
> > "filter/resevoir" to keep the main pump from
> overrunning the transfer
> > pump) and the return line goes to the top of the
> tank.
> >
> > Does this help at all?
> >
> > Drew
> >
> > On Mon, 17 Mar 2003, Benjamin Harder wrote:
> >
> > > AFAIK, none of the mk1 rocco's came with a fuel
> pre-pump installed.
> > > I would like to know (besides wiring issues)
> what, if any, issues there
> > > would be to install a pre-pump?
> > >
> > > The main reason for asking is an experience I
> had with my former '81
> > > while autocrossing... I had about 1/4 to 1/3
> tank of fuel...
> > > coming around a long sweeper (left-hand turn)
> and then onto a straightaway
> > > the car would starve itself for fuel and
> sputter. Not good while trying
> > > to race! So, the issue was obvious to me... the
> car really needs a
> > > pre-pump, or of course just a full tank of
> fuel... which isn't always
> > > the best idea on the track...
> > >
> > > Anyhow, any experience with this one would be
> appreciated!
> > >
> > >
> > > =====
> > > Benjamin Harder
> > > 86 Scirocco 16v
> > > 80 Scirocco (new engine is almost ready!)
> > > 93 Passat GLX
> > >
> > > http://www.geocities.com/vwtype53/
> > >
> > >
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> > >
> >
> > --
> > /=============================================\
> > | 84 Wolfsburg Edition TurboDiesel Scirocco |
> > | http://scirocco.cs.uoguelph.ca/gtd |
> > \=============================================/
> >
>
>
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