mileage computer for a carbureted engine

[diesel_john]

Originally Posted by dcb

Or you could use a supermid ($170) and just figure out how to get the marble signal to look like injector pulses. The RPM displayed would be way off (and possibly the duty cycle), and it is only in metric units currently, but it would be a lot smaller than a laptop.

http://www.greenhybrid.com/discuss/f...-1-t-1-a-3015/

speaking of pulse, would the supermid read the pulse from this fuel pump proportional to fuel volume. this type turns on below 2 psi and turns off at 4 psi. duration wouldn't change but frequency would increase and decrease with fuel usage.

http://www.facet-purolator.com/solidstate.asp


personx, what psi do need for your carburetor?

[dcb]

I'm having an epiphany in slow motion here.

I don't know if that pump will squirt out the exact same amount of fuel with each stroke/revolution, not like a gerotor pump would, but it might be close enough.

But if a pump (any pump) can turn on and off by itself within a pressure range as needed, then perhaps it is simpler and also "close enough" to just keep track of how long the pump has actually run. I.e. an 12 volt analog clock in parallel with the pump for proof of concept. It wouldn't be terribly instantaneous, but would be good for a trip. I think I'll have to try that, maybe a vacuum guage can close the gap on the lack of instant mpg.

therefore we have: miles traveled/(total seconds pump was on ON * average gallons per second the pump moves when installed)

Just have to log the start time, and the start miles and see how close it is at the next fillup to figure out gallons per second the pump is moving.

[diesel_john]

this bike computer is less than 20 bucks and it can count magnetic pulses per hour. so you would have "live" fuel volume per hr.

http://www.cateye.com/sites/cateye/u...s/en/VL500.pdf

so i borrowed the little woman's speedometer off her bike and placed it next to an operating fuel pump, and the display says i going 175 km/hr.

on the bike there is a lower limit on speed, below which, the display goes to zero. this occurs at 2 Hz more testing is needed to determine if the pump will trigger the counter at vary low volumes. or what the flow rate is at 2 Hz. i am thinking make the volume of the pipe after the pump very non-compressible so that the accumulated pressure drops rapidly, there by
causing the pump to cycle on and off (short cycle) for a small volume of fuel.

this bike computer has better spec's, if they are true. $22 (topeak 130)
http://www.topeak.com/sub/documents/M-TPC3-GB-5-05.pdf

[dcb]

Originally Posted by diesel_john

this bike computer is less than 20 bucks and it can count magnetic pulses per hour. just tell it you have a big wheel for more resolution

http://www.cateye.com/sites/cateye/u...s/en/VL500.pdf

so i borrowed the little woman's speedometer off her bike and placed it next to an operating fuel pump, and the display says i going 175 km/hr.

That's awesome

Hey, does that pump shut off when the pressure is reached or does it just keep running?

[diesel_john]

this version of the pump i have does not shut off, it runs continuosly when i dead head it with a needle valve. so i am looking around for an oil pressure switch or something i can throw in line with it. then i can check different flows vs. time.

[dcb]

Wow, you've got it all set up there. Course we are up to $80 with pump/bike computer/pressure switch.

I really like the bike computer idea, they are like $10 at my local store. Even if it is just fuel consumption and not mpg it can be real useful on a regular route. It could be adapted to optical operation easily enough.

Perhaps, with a "marble", or turbine, or paddlewheel, or?? optical arrangement in the fuel flow, and some fudging with the wheel size adjustment on the bike computer, it could be possible to come up with a useable fuel consumed number (or factor of 10 number) in the distance travelled display (or the current consumption rate in the mph display).

Google check time: the bike computer idea is tried, with a $60 sensor. The second link has a schematic:
http://11109.rapidforum.com/topic=11...6&search=sigma
http://diverse.freepage.de/cgi-bin/f.../fuelmeter.htm

[dcb]

Note: it specifies .025L/min on the low end of the sensitivity range on that sensor. It won't even notice my 250 idling.

[diesel_john]

so lots of options on a display but the inexpensive flow meter prob. remains.

the pressure sw idea is proof of concept with the stuff i have. the on/off pumps are in the $40 range. i am just interested in how much fuel would need to be bleed off to lower the line pressure from say 4 to 2. that pump needs to restart a couple times a second for the frequency to be high enough to trigger the bike computers.
the close tolerances on the small flow meters keeps the cost up.

[dcb]

Ok, here is a thought, kind of plays on the drip idea, basically use a bike computer or whatever to keep track of metered units of gas. No real tight tolerances required except the solenoid valves need to work. Now just an electrical problem Again! Will be near-real time depending on capacity of the resivoir and flow, I'm fine with a 10 second delay at full throttle myself if the valves will last 10 times longer as a result.



Assuming circuitry to make it all work (the controller), theory of operation:

start state: valve B is closed, valve A is open, fuel is flowing into the chamber and raising float C.

1. opto-coupler d1,d2 is interrupted by the float and the controller closes valve A and opens Valve B. The float begins to decend.

2. opto-coupler e1,e2 is interrupted by the float and the controller closes valve B and opens Valve A and sends a trigger to the counting device (i.e. bike computer).

3. goto 1

Still need to sort out venting the resivoir when the float is supposed to be moving...

[diesel_john]

reminds me a little bit of the old style gas pump, where they pump how much you want up in the glass cylinder on top to measure it, and then let it drain down into your tank. don't see why it wouldn't work, gets around the low flow problems, and some of the sloshing problems.

i was sort of kidding when i said we could count the drops like an IV dripper, but the way you got those photo sensors mounted it would count the drops, just like my planter counts every seed it plants with an infrared sensor and IR light. might have to put a little dye in the fuel to make it show up better.

on those bicycle computers, do they just have a reed switch inside or a mag. pickup? because a reed sw might be vibration sensitive.

dcb, how did you draw that?