fuel flow sensing

[Jason Lewis]

Hi,

I have a question thats not really on topic.

I'm building a trip computer for my car, and i'm after some sort of fuel
flow sensor so i can measure how much fuel im using (btw, my car still
carburetor)

The only flow meters i  have seen were really expensive, i was wondering
if anyone knows where can get one quite cheaply. (preferably in Australia)

thanks in advance

Jason