Fuel Flow Sensor - Water Flow Sensor

I bought a boat years ago. It has an issue with the fuel level reading. I tried replacing the level sensor, but since it isn't accessible, I decided to build a small device to count the liters of fuel consumed.

I was quite satisfied with the flow sensor coupled with a lcd 4x20 display

I decided therefore to upgrade the system to include a touchscreen for trim control based on speed, throttle position, and pitch.

After some trials on the sea, I recognized that several aspects should be improved; calibration of gyros, calibration of the flow sensor, better water tightness of the display ...

This instructon are focused on diy fuel flow sensor. My idea is to describe later the improvements on the other components of the system.

The sensor is tested between 1.8 liter/h up to 30 liter/h with a pressure drop of 0,08bar.

The range should be extended by replacing the nozzle inside, but for my Evinrude eTEC 90HP 30 liter/h is more than enough.

ITEM Qty Description

1 1 Hall sensor 3144

2 2 Small magnets

3 1 Microcontroller

4 3 Printed subcomponents

5 1 O-ring OD:10.5mm, sez: 2mm

6 1 8x1,5mm Cylindrical Pin 304 Stainless Steel

7 2 Brass fitting M8x1 x 8mm

BOM with link in the attached PDF

3d printing is a tricky technology for this watertight application because normal prints leaks. The setting of the machine shall be quite delicate to make layers properly sealed. Of course the setting has a direct impact on tollerances.