Saga continu.... 100q wont start now

Denis sparkplugvw at
Thu Dec 16 22:29:03 EST 2004

  That s the reply i was expected. I saw somewhere a good explanation of the CIS-3,,, lost it..

  There is ,,, i have a way to go...
  I ll begin at the beginning.
  Check where the fuel start..... filter in the fuel pump.
  Check the fuel line under the car.

  If its ok... then the regulator.
  I have an extra from a 5000T 1985.

  So the fuel pump is almost new, it should be ok. As you said the regulator might not working propelly.

  One more question:
  The fuel  pressure drop instant... at 20 psi when i stop the engine.... is not suppose to be maintain longer ?

  While i m doing it , pray for me.

  Thanks to outlook to check my spelling. :-)
  If its not ok, it s not my fault :-)

  I did that today:

  At the tank 1/4 i added 99.9%alcool in case of water...
  Changed the batterie; the starting procedure got my batterie. Now it spin the engine very well.
  Changed fuel filter.
  I ll partout the turbo distr. to get the reg.
    ----- Original Message ----- 
    From: SJ 
    To: quattro at 
    Cc: Denis 
    Sent: Thursday, December 16, 2004 10:08 PM
    Subject: Re: Saga continu.... 100q wont start now

    > From: "Denis" <sparkplugvw at>
    > Subject: Saga continu.... 100q wont start now
    > I m ver very close to send the car to the junk..... it really bugs me.
    > I change fuel filter , now it leak each side of the fuel filter,, i
    unscrewd..... move parts , screw again and again and again still fuel leak
    i m just thinking put the fire on this fuc...... car .
    <snip the rant>
    > I changed the meter and it tells 70lbs,,,,, but the vac stil 9psi  half
    that it suppose to be.....
    > Now since an hour i put fuel on each cyl to make it turn.... after couple
    pouf pouf  ,, it stop,,, the sparkplugs are dry... so no fuel goes to them
    > Ðenis

    Looks like a fuel pressure problem. The fuel pressure is maintained and
    controlled not by the fuel pump, but by the fuel pressure regulator which is
    located after the fuel distributor.
    The pressure regulator should maintain system pressure between 88 and 94
    The fuel injectors open between 62 and 67 PSI.

    You only have 70 PSI, thats barely enough to open the fuel injectors.

    In the CIS system, fuel is always flowing from the gas tank and back to the
    gas tank. Fuel pump to accumulator, to filter, to fuel distributor, to
    pressure regulator, back to fuel tank. Its that pressure regulator at the
    end of the line that maintains system pressure at 90 PSI.
    If the pressure regulator is shot . . .wide open . .you will get very little
    system pressure . . .lots of fuel going round the circuit, but no pressure.
    If the pressure regulator is stuck shut . .. you will get the the pressure
    that the fuel pump can deliver . .. which I asssume would be over 100 PSI,
    but no fuel flow back to the tank. I would think the fuel pump would burn
    out pretty quickly under this condition.
    If the fuel pump cant deliver the required pressure . . at least 90 PSI. .
    .the pressure regulator is in the closed position . fuel flow. This
    might be a good place to check. and work backwards from there.

    Usually the culprit is the fuel pump. Clogged fuel lines can be another
    problem. Clogged fuel screen inside the tank.


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