Date: Sat, 21 Jul 2007 08:39:11 -0700
Reply-To: David Kao <dtkao0205@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Kao <dtkao0205@YAHOO.COM>
Subject: Re: Will not start question
In-Reply-To: <296481.13162.qm@web82704.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
If I remember correctly the 4 injectors are not individually driven
by the ECU. I once studied the ECU and found the 4 injector wires
being tied together and driven by the ECU all together, which is by
grounding it. I could be wrong but I seem remember about this.
David
--- David Kao <dtkao0205@YAHOO.COM> wrote:
> I just looked at the electrical diagram on my Bentley manual for the 84.
> It looks like all 4 injectors receive positive supply (+12V) from a same
> common source which also supplies the positive terminal of the fuel pump.
> This +12V is coming out of the fuel pump relay. This +12V is controlled by
> the fuel pump relay. The +12V will be present when the relay is activated.
>
> So you want to check if all 4 injectors are getting this 12V at the same
> time when you are cranking the engine by the starter. You should get a
> steady light from one of the pair of the wires on every injector. If the
> fuel pump is pumping (getting +12V) all 4 injectors should get the same
> +12V as well. Let's call this wire of the injector the first wire of the
> two wires of the injector.
>
> An injector will inject fuel when the 2nd wire of the pair is grounded
> by the ECU. This is because the first wire is connected to +12V. The ECU
> should ground the 2nd wire for each injector momentarily in a round robin
> order to fire the 4 injectors when you are cranking the engine.
>
> If you connect one lead of your tester to the 2nd wire of the injector
> and the other lead to the ground and crank the engine your tester should blink.
>
> If you have replaced the ECU you may want to check if the +12V is pressent
> at all 4 first wire of the injectors. This +12v is also the same +12V
> supplying the Fuel pump. Check your pump to see if it is pumping when you are
> cranking the engine.
>
> David
>
>
> --- "Randy C. Nunes" <randycnunes@YAHOO.COM> wrote:
>
> > Thanks everyone for your suggestions! Wanted to provide some more
> > information as my cryptic message from last night was a result of me being
> > pretty tired worked on it for six hours with no real conclusions. I was
> > backing it up last week and it just stopped - tried to resart no go. There
> > is lots of spark, lots of fuel pressure, it turns over every time. The
> > injectors are just not firing, changed out the ECU, no change; checked the
> > AFM, it appears to be working. There is something wrong with the electrical
> > current getting to the injectors - which I thought was controlled by the
> > ECU. When you ground the light to test the FI electrical connection and try
> > to start you get the pulsing light, when you connect the ground to one of
> > the two FI connections and try to test no pulsing light.
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> > ROBERT O UELTZEN
> > Sent: Saturday, July 21, 2007 1:48 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Will not start question
> >
> > Along with all the other possibilities mentioned, you might check the
> > ignition switch. I was
> > having an intermittent no start and engine dying condition on a 91 Jetta.
> > Eventually, I worked
> > back to the ignition switch. Upon opening up the switch, I found corroded
> > contacts. A new switch
> > solved the problem.
> >
> > Rob, the old kayaker
> >
>
>
>
>
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