Here is a low cost fuel flow meter from Tracy Crook that should work
with just about any engine using four electronic injectors.
With minor modifications it can be used with any number of injectors.
I redid (cosmetically) Tracy's original schematic somewhat.
With his permission I will post it on the ACRE NL web site.

Paul Lamar

 Paul, I could be mistaken and its a minor point, but I believe that the
injector pulse voltage varies from around +13 volts to near zero.  The diode
is back biased by the 5 volts regulated Vcc so that it only conducts when
the injector voltage on the diodes base drops below 5 volts.  So you have a
13 Volt pulse train to the diode and a 5 volt pulse train after the diode
which the 74HC04 then inverts.  The steady 5 volts is need to that the
capacitors charging curve stays constant.

Ed

I think you are right. I just corrected the schematic.
I think most EFI systems switch the ground side of the injector solenoid.
That is why they use two wires.
Thanks for catching that.

Paul Lamar
 
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