I've been thinking of this also.
Unfortunately my vehicle DOES have both carburettor and return line. (as do
many other carburated vehicles I've encountered since about 1970).
The approach I've been considering is having 2 ptc resistors, connected in
a bridge arrangement and one in the go and the other in the return line. A
simple diffamp (or differential input ADC) is then all that is required,
along with some sort of lookup table.
Fuel temperature variations should be common to both so will largely
cancel.
This would then give a litres/minute reading which could be combined with a
km/hr pulse to get litres/km or 100km/litre or mpg etc.

The only real tricky part is mounting the PTCs -  but this could be
external on a copper pipe segment (insulated) so direct contact with the
fuel may not be required. Just need to keep the overall mass to a minimum

Richard P



> What about carbureted engines in applications other than automotive?
(like
> the one I'm thinking of ;) )
> The well discussed principle of injector pulse proportion &
> pressures won't
> help in these cases......

        In that case the next easiest method would be a fuel flow sensor,
fortunately most (all?) carbureted engines do not have a return line so you
only need one sensor. TTYL

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