Low cost fuel flow meter

Here is a low cost fuel flow meter from Tracy Crook that should

work

with just about any engine using four electronic injectors.
With minor modifications it can be used with any number of

injectors.

I redid (cosmetically) Tracy's original schematic somewhat.
With his permission I will post it on the ACRE NL web site.

Paul Lamar

Will this work with subtracting the fuel in the return line?

AI Nut

Yes it will as all it does is measure the fuel coming out of the
injectors. Many car computers use this info to calculate the instant
and average MPG and display it on the instrument panel. My 1992 Dodge
Caravan has such a display.

Paul Lamar

Paul,
What would be required to use this on a 20B??
Don

I suspect minor changes in some of the resistors. Perhaps a 50% decrease

in the

value of R4. Perhaps Tracy knows exactly. The principle I think is it is

only

looking at one injector pulse and the circuit assumes there are four

pulses.

Is this correct Tracy or is your computer computing the combined data
and putting out one pulse trains with period and width adjusted

accordingly?


Of course the max reading in a 3 1/2 digit 0.2 volt voltmeter would be

or 19.99 gallons per hour. Some other voltmeter module probably should be

used

because at full power full rich 20B will probably suck down more than

19.99

gallons per hour. One could of course move the decimal point but the DC

input

voltage to the voltmeter would be further down in the noise level at low
fuel flow rates. Long story and it would take several paragraphs to

explain

this better. Better to change the voltmeter IMHO to something else like a
full four digits. I'll be interested in what Tracy has to say about this.

Paul Lamar

There is probably enough range with the values shown to work with the 20B.
If not, change the 3.9 Meg resistor to 3.0 meg.  Paul is correct about the
range with these values.  As an alternative, you could change the 1 meg pot
to a 100K pot and jumper the display decimal point to the next place right
(instructions come with display on how to do this) and it would indicate
from 000.0 to 199.9 gallons per hour.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com


 
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