Date: Sat, 21 Jul 2007 07:58:43 -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: <!&!AAAAAAAAAAAYAAAAAAAAANM2reyyaLlCr/d6q6Fh77nCgAAAEAAAAN8CVeCkAvFDjq0KC069ckMBAAAAAA==@yahoo.com>
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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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