Dear t vago,
I tried unsuccessfuly to get more info about the fuel meter you recommended to me at first, the 13mm red one, no Brand one. I forgot my password in EBay and these guys insisted in sending me codes to my line phone, which are unusable.
But I searched myself in a chinese provider and found this:
G1/2" Diesel Gasoline flow meter,Gear flow meter,Fuel oil flow sensor / Counter-in Flow Meters from Industry & Business on Aliexpress.com
If you look carefuly it is the same fuel meter, and happend to be a reliable fuel metering method or mechanism and it is a japanese one. All that tell me it is more reliable than the majority of them, and very cheap. It makes sense to me that it is more expensive to buy it from China than from EBay if it comes from Japan.
Can you Access EBay seller to ask him some questions? Hopefully get his email. I need to have two meters and calculate the difference between them to get the fuel used. As he sells a digital display that matches the fuel meter, maybe he may have a differential meter too.
In relation to your momments, yes, I had problems computing fuel in Arduino, because of a delays, lack of speed, variations. I tried to compute the mean of ten pulses each time to may the instrument more representative and more stable, but Arduino almost could't cope with that.
And as I told you, when I was getting some stable results, the fuel meters stuck and begin to leak. They were too fragile.
Besides, Arduino program was working well on the protoboard, but when I moved to a stand alone box, it failed miserably. This took me more time to correct and the fuel meters died.
Best,
Oldbeaver