mileage computer for a carbureted engine

[diesel_john]

well i tried in vain tonight to get a bike computer to read the magnetic pulses from 12v solid state fuel pump. the digital odometer would not follow the increasing and decreasing frequency of the pump consistantly when i varied the flow with a needle valve. i had the pump cycling on and off between 2 and 4 psi pressure. but when it turned on each time it had to make 5 or 6 thumps to catch back up to 4 psi. and the bike computer counted those 5 or 6 pulses as 100 or 120 MPH instead of the actually fuel being delivered which was 20 or 25 MPH. the other style pumps that are longer and cylindrical might pump more volume in one stroke an work better, also the pressure switch i was using had a 2 psi delta that i couldn' easliy narrow. with a 1 psi or less delta and a higher volume per thump and it might work.

[dcb]

I thought the fuel delivered would have been in the distance travelled, don't know how usefull mph will be without the flow sensor. But if it is still off by a factor of four on distance travelled, then maybe see if you can tell the bike computer that the "wheel" is 4 times smaller in circumference.

The bike computer I had, the sensor would click when I brought the magnet near itm so assuming it was a reed type.


p.s. picture was done in paintbrush, saved to .gif

[diesel_john]

distance times a constant would be gallons but i never got that far, because MPH wouldn't track GPH. MPH times the fudge factor is GPH. the concept has not been dispproven.

[diesel_john]

who, had a pic of the Zemco flow meter. The part on the left is the recirculating ball flow meter.

[AndrewJ]

http://cgi.ebay.com/ebaymotors/Zemco...spagenameZWDVW

[diesel_john]

Originally Posted by AndrewJ

http://cgi.ebay.com/ebaymotors/Zemco...spagenameZWDVW

thanks, AndrewJ I'll watch it. John

it sold for $25plus 6 shipping with a few seconds to go.

[diesel_john]

to summarize so far we have found that some Zemco flow meters are still on ebay and selling for $25 to 30. the output is frequency proportional to fuel flow.

dcb
has found a circuit diagram to convert pulses from a flow meter to a bike computer for measuring mileage on a carb'd engine.
http://diverse.freepage.de/cgi-bin/f.../fuelmeter.htm

also a site showing a bike computer displaying mileage.
http://11109.rapidforum.com/topic=11...6&search=sigma

This makes it possible to measure to mileage of a carb'd engine for about $100 to $120. which is still above our price goal.

[diesel_john]

I found the old flow meter and it looks like it wouldn't be to hard to fix.
Also found old feeding metering pump.

pic 1 both halves of meter showing hole for the light source on left half, mount for photo resistor on right half.

pic2 input side showing flow damper and metering jet

pic 3 also found a precision flow up to 295ml/hr. (tube stretched over rollers measures the fluid.)

pic 4 drop detector assembly for the medical flow meter

[dcb]

Cool, what is the diaphram about? Is inlet pressure applied to the non-spring side?

I just realized looking at this that the "marble" is probably the same "density" as gasoline. A heavy marble might not be as accurate, it would have too much inertia, and tend to sink to a low spot, and a light one would tend to float.

[diesel_john]

Originally Posted by dcb

Cool, what is the diaphram about? Is inlet pressure applied to the non-spring side?



I just realized looking at this that the "marble" is probably the same "density" as gasoline. A heavy marble might not be as accurate, it would have too much inertia, and tend to sink to a low spot, and a light one would tend to float.

yes, the spring pushes against inlet pressure.

The diaphram is an accumulator to damp the fuel pump pulses. Providing a more constant pressure to the restricting nozzle. Which is just brass jet.

The correct ball was made of hard plastic or rubber and was the same density as gasoline. It melted either from heat or fuel. the ball needs to be opaque. The ball in the photo is for illustration purposes. It is from a straight pin and the wrong material. I am looking for a black 0.250" glass or plastic ball.

the light source failed and I am going to replace it with a LED. But even with a ball bearing in inside and my flashlight, I can get the display to count fuel by blowing thur it.

I am going to put it on my mechanical injected diesel.