photo of internals : 13mm G3/8" milk honey diesel gasoline oval gear flow sensor meter Liquid Fuel Oil Flow controller Counter - buy at the price of $13.02 in aliexpress.com | imall.com
interesting gear type sensor.
it is not a screw connection and the body is made of plastic.
I would want to know a the working pressure.
it looks like the end is thing plastic with and o-ring.
This one may not be perfect, but a flow sensor is the way to measure one of the main parameters.
back in the 70's bell-bottoms were all the Rage, the Beatles were still loved and one could get an after market economy computer that would tell MPG and distance to empty. I would look to see if any of those are still around.
while a lot more expensive:
Garmin Gfs 10 Fuel Sensor For Gas Engines Only
This is sold expressly for gasoline.