Date: Fri, 28 Dec 2007 18:25:11 -0800
Reply-To: David Kao <dtkao0205@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Kao <dtkao0205@YAHOO.COM>
Subject: Re: Daily Update On My Injectors
In-Reply-To: <000a01c849bb$ce8b5950$6401a8c0@TOSHIBALAP>
Content-Type: text/plain; charset=iso-8859-1
Scott, you have good reasons to doubt about this.
My thought is if the ECU is not grounding the leads to one of
the two leads of each injector the 4 leads are effectively open.
If the other 4 leads are connected to 12 volt at the fuel
pump relay then the floating 4 leads will be also at the
same 12 volt as the other leads are. In other words the two
leads of each injector will be at the same voltage of 12 volt.
Inside the injector is a coil, a conductor with 15 ohms resistance.
This is why both leads are at the same voltage. When ECU grounds
one of the leads the 12 volt difference forces current to flow
through the coil which then pulls the solenoid in the injector to
spray fuel.
Well, it may be any voltage depending the voltage the fuel pump relay
feed to the injectors. So you are right it may not be 12 volt.
Hope I make better sense this time. Correct me if I am wrong.
David
--- Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM> wrote:
> Well David............mostly all pretty true.
> I'm not so sure about this one though :
> " With the ignition on but engine
> not running all 8 injector leads should give you 12 volt reading."
>
> There's no reason to be looking for 12 volts on the wire that comes from the
> ecu to the injectors and supplies ground for the injectors. It's not logical
> to look for 12 volts on that wire, it wouldn't have any purpose.
> Scott
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> David Kao
> Sent: Friday, December 28, 2007 5:19 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Daily Update On My Injectors
>
> Now that you have tried so many ECUs it is indeed very unlikely all of them
> are defective. You may have a wiring problem.
>
> The Bentley shows that one of the leads of each injector are connected
> together
> and is fed with power from a relay called fuel pump relay. The other led of
> the
> injector goes into the ECU then all 4 of them are combined into one and
> connected
> to the solid state switch in the ECU. If the switch is turned on (shorts the
> 4 leads to ground) the injectors will spray fuel. So with the ignition
> switch
> turned off none of the injector leads is grounded. With the ignition on but
> engine
> not running all 8 injector leads should give you 12 volt reading.
>
> Pin 7 of the ECU is ground for ECU. It has nothing to do with the injectors.
>
> When you turn on the ignition key did you hear the fuel pump humming for a
> few
> seconds? That's the fuel pump pumping up the fuel pressure. If you did not
> hear
> the hum you may have a defective fuel pump relay. There are two relays in
> the
> relay box. The 2nd one is called power supply relay. If any of the two is
> defective
> you have not hear the fuel pump humming. You will not be able to start the
> engine.
>
> Good luck.
>
> David
>
>
>
>
>
> --- Vdub Guy <fonman4277@COMCAST.NET> wrote:
>
> > OK, <sigh>, today I obtained not one but 2 used ECU's, 6 used injectors,
> and while I was at it
> > got the entire wiring harness out of a 1.9 Vanagon. Both ECU's give the
> same result as my other
> > two. Now the 2 I got today were used and unkown, but doubtful I have 4 bad
> ECU's. Thanks to
> > those who pointed out I was checking the fuel injectors incorrectly with
> my meter. Set at 1X I
> > get 15-16 ohms. Now, I started dissecting the harness I got (damn sure
> less complicated than the
> > mountain of wiring I have in my basement from my Suby donor!). From the
> ECU plug I found
> > continuity between pin 7 and brown wire with a white tracer ,which goes to
> the cluster of
> > grounds on the head. I assume pin 7 is ground to the ECU, as each injector
> shows one side to pin
> > 7 (Bentley). I did NOT get continuity from any of the injector plugs to
> pin 7. So, I head out
> > to the Vanagon, unplug the ECU, I get continuity from pin 7 to the head. I
> also get continuity
> > between one side of each injector plug and pin 7. So, I
> > 'm not sure what this proves, other than I have ground to pin 7 at the
> ECU, but when i check the
> > FI plugs on the engine, apparently no ground with ignition on, engine
> cranking-test light
> > doesn't flicker. Jeff
> >
>
>
>
>
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