>>     The only problem is I don't know where you would get the injection
>>     quantity per pulse value, but it might be in the shop manual for the
>>     vehicle in question.


>Fill the tank, zero the counter, drive for a while (the longer the better)
>refill the tank, and enter the fuel quantity used to refill.

>During this process, we've been counting injector pulses, so we now
>know that there are X pulses per gallon. (liter or whatever)

Hmm...
How can this be correct?
It will probably get you in the ballpark, but all you get is an average.
To measure instantaneous fuel consumption you will have to both time and count
the injector pulses for a very short period of time. The amount of fuel flowing 
in
the injector is constant while it is open, and therefore you have to measure 
for how
long it stays open. This is typically in the ms range. When you know this you 
can calculate
fuel consumption.

-Oyvind