[T3] Car Cures Itself...

[Dave Hall]

One of our UK club members investigated this carefully on his Type 3, and
found that there can be 'micro-leaks' in the piping that don't leak fuel but
do allow air into the pipes over a time.  He replaced hoses and the pressure
fall-off was greatly reduced.  I assume his fuel-pump non-return system was
still functioning OK.  

I've seen figures for the ring main pressure fall-off in a VW manual and
seem to recall a figure of around 10psi even after a number of hours.  That
would assume a perfect system.  These days FI pumps seem to run the moment
you put the key in, and I believe some even do it as you unlock the car.

It won't be long before it uses telepathy to work out that you are about to
leave the house to get in the car!  I suspect some cars already know our
intentions.  Shades of Herbie.

Dave
UK VW Type 3&4 Club
===================

 

-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Tony
Rongey
Sent: 27 June 2013 14:20
To: type3 at vwtype3.org
Subject: Re: [T3] Car Cures Itself...

Jim,
I thought you were the one who explained this to me, but it might have been
Russ or Tram.  The theory that I've heard is that the engine heat causes the
fuel in the exposed fuel hose to evaporate.  Since our cars are full of old
worn parts neither the pressure regular or the check valve in the pump are
up to the task of holding pressure for very long.  Once everything cools
down you're left with a fuel system full of low-pressure vapors so the whole
ring has to be loaded up before it will start.
Sounds to me like he needs your fuel pump rebuild (if you're still doing
that), because his check valve has failed.
Tony
'70 Fastback AT/FI daily driver

From: Jim Adney <jadney at vwtype3.org>
To: type3 at vwtype3.org
Sent: Wednesday, June 26, 2013 10:33 PM
Subject: Re: [T3] Car Cures Itself...


On 26 Jun 2013 at 17:38, J. Jonik wrote:

> By the way, it SEEMS that if I prime the fuel pump about five or so
> times before trying to start, THEN it works ok from the start....most
> (not all) of the time.  

...I don't understand why this happens, but an engine that's shut down 
hot and allowed to sit, will get air in the fuel ring around the 
engine. Until the air is all gone, the cylinders won't all run well, 
...
-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************

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