Fuel Flow Problems

[amalventano1@comcast.net (Allyn)]

    yea, i can second that. as you drive for 10 minutes, air accumulates in the
reservoir (between the tank and main pumps). this happens because there is an
air-return tap off of the top of the reservoir. normally the transfer pump keeps
the reservoir at a pressure and air escapes back to the tank through this line.
with no xfer pump, the reservoir runs at a vacuum, drawing air in the top line.
once the reservoir fills with air, the main pump sucks it in and your engine
dies. once it dies the main pump cuts off and the reservoir is able to fill once
again (from the tank, via gravity).

    2 things have to happen at once for this to happen:
1. xfer pump bad (not pumping / flow below capacity of the main pump). also note
the xfer pump might be ok, it has a suction screen that may have simply clogged
instead.
2. the return hose on the transfer pump assembly has to be broken (it tends to
get eaten by many years submerged in fuel, so this is quite possible). if this
line wasnt broken, the reservoir would never fill with air, it would feed from
the bottom of the tank instead.

if you have this problem and you floor it, the main pump cant keep up and dies,
explaining your other symptom.

btw, welcome to the list!
Al

Allyn Malventano, ETC(SS), USN
87 Rieger GTO Scirocco 16v (daily driver, 180k, rocco #6)
86 Kamei Twin 16V Turbo Scirocco GTX ('it has begun', rocco #7)
86.5 Occo 16v Trailer (dotting 'i's across the country, rocco #8)
87 Jetta 8v Wolfsburg 2dr (daily driver, 260k, 0 rattles, original clutch,
driveshafts, wheels :)

----- Original Message -----
From: "Daun Yeagley" <vwdaun@yahoo.com>
To: "Louise McCormack" <louise_mccormack@hotmail.com>; <scirocco-l@scirocco.org>
Sent: Monday, August 26, 2002 1:54 PM
Subject: Re: Fuel Flow Problems


>
> --- Louise McCormack <louise_mccormack@hotmail.com> wrote:
> > Hi Everyone,
> >
> > My husband recently bought be a 1984 Scirocco 1.8 8V GL
> > I'm very happy with the car, apart from a recurring
> > problem.  If you drive it for about 10 minute, it starts
> > to backfire and then cuts out totally.  After 5 minutes
> > you can start it again, drive for 10 minutes and the same
> > will happen.  Unless you drive it hard, then it was cut
> > out straight away :)
>
> It sounds like the in-tank fuel pump - but we need to know
> if your car has it or not.  (It was introduced mid-year
> 1984)  Easy way to check is to see if you have a full size
> or 'space saver' spare tire.  If you've got the space
> saver, you've got the in-tank pump.
>
>
> =====
> Daun Yeagley - Wilmington Ohio
> '80 S, 81 S, '86 & '88 Sciroccos, 90 Passat Wagon
> For Sale: '82 Scirocco, '82 Pickup.
> Parts cars:  '81 Scirocco, '87 Scirocco 16v - ASK!
> "A learning experience is one of those things that says, 'You know that thing
you just did?  Don't do that.'" - Douglas Adams
>
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