I'm guessing less than .1gpm at idle.
Anyway, I like the pressure switch idea now
I got a
Low Pressure Switch off of ebay. This setup is showing some promise, but my bike computer is freaking out with all the noise from the pump (resetting and not in a useful state). It is actually on the bike and mostly hooked up though, so that is extra promising
I can blow into the tube and make the computer count, so it is electrical mayhem. When I use my thumb to controll the pressure, the pump pumps up and shuts off fine, but the computer freaks.
Theory of operation:
The pressure drops as fuel is consumed,
the N/O part of the switch closes and the pump turns on,
the N/C part of the switch opens, the computer does nothing
the pressure builds back up,
the N/O part of the switch opens and the pump turns off,
the N/C part of the switch closes and the computer registers a tick
(just guessing) the pump flow rate is probably 100 times the max consumption rate of the engine, so any variance in fill volumes between low consumption times and high consumption times will be minimal.
The number of pump cycles will be porportional to the fuel consumed (fingers crossed).
Note, there are no electronics at all currently, excepting the bike computer.
more reading:
a foot of 3/8 tubing helped installation. Store only had 3/8 tees and I added a 3/8 check valve just downstream of the pump because it wasn't sealing reliably (I don't think it liked the water experiments
, what with the black stuff coming out). The rest is 5/16, occasionally jammed onto a 3/8 plug, plus a few 5/16 nylon tube joiners. Attaching the pressure switch cheaply was accomodated by grinding off the threads and shoving it into some 3/8 tubing.
Maybe I just go to sciplus and get a few mechanical counters w/resets(one for current and one for tank tracking), and put this computer back on a bicycle