Injector Flow Bench - Schematic Available

[Frederic Breitwieser]

>Have any of you guys out there made a Fuel Injector cleaner/flow bench
>be it stand alone or PC controled?????

Hey Justin,

I made both a self-sufficient system as well as one controlled by the
parallel port, using the same basic schematic, in JPG format.  Sorry its
such a big JPG, I drew it freehand in Visio since I was too lazy to convert
the real schematic from Orcad to something else that's usable.

	http://xephic.dynip.com/hb_efi/injectors.htm

That URL has the schematic, but let me explain a little bit how to hook it
all up.

First, you need the items in the schematic, something to solder it together
on, and heat sinks for the NPN 2N3055 transistors.  They definately get
hot.  Probably too hot, but I had a box of them so I didn't care.

You need tall, narrow GLASS cylinders, like those things they sell in
Edmunds Scientific.  I, being really cheap, bought 6 "7 day candles", which
are nothing more than a 12" high by 3" wide pyrex beaker with a
dopey-colored candle in it, for a buck each at Walmart.  I burned the
candles out, then ran the pyrex through the dishwasher as to remove the
remaining wax.  Once you have six clean beakers, you make a metal plate
that sits on top of all six beakers, with holes to fit your injectors.  I
don't remember offhand what size the hole is, but I measured one of the
injectors and simply drilled to fit.

Then, I took two fuel rails I pulled from a junk car (along with the
injectors of course), connected the injectors to the rail, jerry-rigged a
clamp to hold them still on top of the metal plate, and connected the two
fuel rails to an in-tank GM fuel pump, the pump being submerged into a
metal bucket containing mineral oil or something like that.  I used
gasoline, and I must admit that was very stupid.

Once the pump is fired up, you get approximately 50lbs of fuel pressure,
because there is no regulator.  I got 51lbs of pressure on the guage I
inserted into the line.  Turn on the circuit, and bleed the air out of the
system through the injectors, until all of the air is gone.

Then, turn it off, lift up the metal plate on top of the beakers (injectors
should be firing into the beakers by the way <smile>), and dump them back
into the bucket.

Now, turn the circuit back on for a specified amount of time.  If the
injectors are equal, they will fill the beakers to the same height.  If
they vary more than 3-5%, I'd try other injectors until you have a
near-matched set.  I went through about 20 junkyard injectors before I
found six that worked well.

BTW, I'm building a six cyl engine, hence my desire for six injectors at a
time.  You can do four, five (if you have an Audi), eight, etc, however if
you are firing off eight injectors, you might find that your 12V power
source will be weak, unless you are using a fully charged 12V battery, or
something like a 50A power supply.  I bought one years ago at a flea market
and use it for just about everything except for welding <G>.

If you want to change the circuit to be driven off your parallel port, you
can dump the entire 555 section, and simply use the parallel port to drive
the input on the inverters, and have the printer cable share a ground with
the circuit as not to damage the CMOS parts.  Be sure to use a auto battery
instead of a power supply, just in case somethings not grounded properly,
it would suck to lose your system board.  I successfully did this, actually
first, before the 555 timer version, but realized it was too much work to
use a laptop, with 10 lines of code to keep writing 00111111 to the
parallel port every few milliseconds.  A 555 timer for 20 cents just the
job just fine.

Hope I helped you :)


Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/

:When in doubt, by two."
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