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