The TS is in India. Western concepts of accuracy and regulation, outside major cities may not apply (or even in them, based on my limited experience of working there in New Delhi and Bangalore in the late 1990s).

So what the TS wants, and should have explained at the start, is to measure, more accurately than the fuel gauge (which on most cars is fairly inaccurate anyway) how much fuel has been deposited in the tank by measuring the flow rate over time in the filler pipe.


A suitable fuel-rated sensor of the type suggested, measuring flow over a time-period triggered by a non-zero flow rate should be good enough, say within a few % points, to determine whether short-fuelling has occurred.

A simple single board computer, eg ESP32 or similar and an app on the phone, communicating via Bluetooth is easy to implement (i did something not dissimilar for a tachometer a year or so ago) and works well in an automotive environment subject to good supply rail regulation and decoupling (i recommend an isolated dc-dc converter, it just makes its so much easier to get a clean supply).

@Irving Precisely, thanks for further elaborating. I will try with ESP32 or an arudino. I'm further emphasizing to keep it simple on display meter rather than the bluetooth connected app.

 

As i said in post #15

"The TS is in India. Western concepts of accuracy and regulation, outside major cities, may not apply (or even in them, based on my limited experience of working there in New Delhi and Bangalore in the late 1990s)."

I got that now and yes, things would have gone better had that been posted originally. My best guess is still using a flow sensor in a totalizer function. The sensor would be mounted in the fuel tank inlet and the overall accuracy should exceed whatever anyone plans to challenge. My days for India and Pakistan were early 80s. Loved the Indian food, still do. Aside from weighing which could get complicated requiring major alterations my suggestion is a flow sensor designed for fuel and set up to run in a totalizer mode. Any of several circuits can be used including a uC. Fuel flow measurments to include rate and total are pretty common.

Ron