Since I've been asked over and over again for the circuit diagram of my fuel meter I have decided to make it available through the Web. Here we go … The basic idea was that a rather huge tank like the one that I am using for long distance trips is very hard to judge, especially the amount of fuel that is still remaining is rather difficult to estimate. This is especially true for dual purpose use (dirt – street). The circuit that is presented in this article solves this problem. The consumed quantity of fuel since the last reset is displayed in liters. With my 43 l tank, the observed precision was about +/- 1 liter, which means an accuracy of approximately 5%. When riding the bike in a rather balanced way on asphalt the expected error should be smaller than 5% since the non-linearity of the sensor below 4 liters/hour can be neglected.
The circuit diagram:
The sensor:
The following parts are needed for “Possi's Fuel Meter”.
Parts order list at CONRAD Elektronik:
- 842737-44 SIGMA Sport BC 700 29.95 DM
- 126055-44 Flow sensor 72.50 DM
- 400378-44 Resistor 10k Ohm 2× 0.20 DM
- 400254-44 Resistor 1k Ohm 0.20 DM
- 453030-44 Capacitor 3.3 nF 0.37 DM
- 481670-44 Capacitor 1 µF Elco tantalum 0.57 DM
- 162272-44 Diode 1N4007 0.19 DM
- 183040-44 Voltage regulator 78L08 0.75 DM
- 175331-44 Op-amp TL081 1.15 DM
- 172758-44 CMOS counter 4020 1.70 DM
- 527726-44 PCB 4.15 DM
- 521671-44 Module miniature housing 1.65 DM
Total: 113.58 DM (catalogue 1997)
Enter tyre circumference approx. 1400 in the Sigma. Then adjust by a few percent according to actual consumption.
The sensor is available through Conrad-Elektronik, Hirschau. All pictures shown are scanned from their catalogue.
Sensor data:
Possi's Fuel Meter as a ready-made module, cast in synthetic resin.
Dimensions (W×L×H): 40 mm × 40 mm × 20 mm.
Plug-and-play with automotive connector connections for +/−, sensor and tachometer output. For the motorcyclist not so gifted at soldering.
Price: 30,– DM (without sensor)
Was available from Chris, Enduro-Stammtisch Straubing
*** Unfortunately the module is no longer in production – as of March 2005 ***
An example installation on a Varadero is described at alpentourer.de here.