Date: Sat, 7 Dec 2013 17:01:08 -0500
Reply-To: Steve Cotsford <cotsford@AOL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Steve Cotsford <cotsford@AOL.COM>
Subject: Re: making a little headway but need advice
In-Reply-To: <52a38ebc.0e94e00a.7d63.2ac9@mx.google.com>
Content-Type: text/plain; charset=us-ascii
Hello David, thank you for chiming in. When I was testing, I was moving the rotor on a partly removed distributor. Consequently, the instant that a Hall effect pulse took place, the injector(s) operated and in this case, the fuel pump operated also. i did not attempt tp make the injector fire more than once. I have returned to the van and repeated the test, this time moving the rotor quicker and repeatedly. The injector fired several times, in time with my movement of the rotor, therefore repeated Hall effect switching while the pump continued to run on its residual time or otherwise. Therefore, there was no connection between the injector firing and the pump stopping. That was an incorrect assumption on my part. My apologies.
When at first I looked for a B+, I found one on both connections of the injector plugs of the l/h bank. Then I could only find one on each plug of the other injector bank. Then when I went back to the first bank, I could only find one, not 2 as I had originally thought. I'm not sure what I did there. Somehow I determined that all 4 injector plugs had the same connections to them and looked no further. Actually I was hoping to find B+ on one bank and not the other (r/h) as this could be why the injectors on the r/h bank would not fire at all.
I have not yet applied my meter to the injectors themselves and perhaps I should. I think I have determined that 3 out of the 4 injectors need attention and need to be made to fire off and I think I turned my attention to a possible way to make that happen without having to replace them if possible. I should go back and do my testing again. Having B+ at both connections did not compute for me at the time. I am not an electrical or electronic engineer. Steve
On Dec 7, 2013, at 4:09 PM, David Beierl wrote:
> At 03:47 PM 12/7/2013, Steve Cotsford wrote:
>> Hi Neil. I did a little more checking. It seems that each FI plug does have a constant B+ on one side. For me it was showing 11.75 Volts As I was doing this testing with the pump relay in place, I noticed that the B+ was only present when the pump was running and when it disappeared and the pump turned off, this is when the injector sprayed.
>
> I'm having trouble following this part. Your injectors should fire independently of the pump running; they're separate activities.
>
> The pump only runs during the period that the ECU is receiving pulses from the distributor (and I'm guessing for a second or two after) as a safety measure so as not to continue pumping fuel after an accident or fuel-hose rupture.
>
> The injectors OTOH fire on each individual pulse from the distributor. Of course if there is no fuel pressure nothing comes out (which is why the fuel pump runs for a couple seconds when you turn on the ignition key, to make sure that the fuel ring is up to pressure), but the injectors fire regardless.
>
> You can easily detect the actual mechanical action of the injector by using a stethoscope (Lisle is a good brand; the one they sell at Pep Boys with a joint in the probe is useless**), or a long metal rod/screwdriver pressed against your ear. The injector makes a very distinct click.
>
> **A good stethoscope will produce painfully loud sounds if you tap the end on something or drag it lightly across concrete.
>
>> I'm not sure what that means and I will have to do some more reading but as the signal seemed identical at all 4 plugs, I'm pretty sure it means that the 3 injectors that are not spraying are doing so because of a fault within them each. Steve
>
> With the system ready but idle you should have B+ on *both* sides of the injector plug. If you don't then there's bad contact at the plug (or an open injector coil, of course). When it runs one side pulses down toward ground for the duration of the injector opening. If your Fluke can measure duty cycle you can see that happening.
>
> All the injectors are switched by the same transistor, so if you're getting pulses on some lines and not others it's a wiring issue.
>
> Yrs,
> d
>
>
| 
