Fuel Flow Meter

[mrriggs]

When researching fuel flow meters I saw some cheap-China fuel flow sensors that cost about a tenth of what a real flow sensor costs. It's probably worthless junk but at only $15.95 [shipped] it was worth a shot. I enjoy tinkering so even if I don't end up with a usable flow meter, it'll still be worth it for the entertainment value.



The flow sensor is from ebay. There are many sellers of the same sensor with different stickers. Mine says, "Made in Japan" [yeah right]. The specifications are completely bogus (0-160 gph, +/-0.5% accuracy). I suspect that the sensor won't register at all at low flow due to it's size and poor internal tolerances.

I didn't want to waste a bunch of time and money on a meter if the sensor wasn't going to work so I'm using a bicycle speedo to read the sensor. I had this on my motorcycle for years but pulled it off when I broke the wheel sensor during a tire change. The original sensor was just a magnetic reed switch that would close when the magnet on the wheel passed it. I played around with a signal generator and found out that it could be fed with a 3 volt square wave. Luckily the flow sensor can be operated on three volts.

For a quick and cheap 3 volt power source I'm using a pocket flashlight. It used a wire-lead bulb so it was simple to pull the bulb out and slide in two wires.

The bicycle speedo is calibrated by entering the wheel circumference in mm. There is 1609344 mm in a mile and my sensor is supposed to put out 8230 pulses per gallon so I told the speedo the circumference is 196 mm [1609344/8230=196]. That way the mph reading on the speedo is actually gph and the odometer is a direct reading of gallons used.

It's all hooked up on the kitchen table and the speedo registers when I blow in the flow sensor. When it warms up a bit I'll hook it up in the car.