> > >Marc Pedings's injector flow tester is working
> >great. Thanks again Marc. I notice the MSD and 2nd
> >gen Nippon Denso injectors work down to about
> >.8 ms. While the red and yellow RX8 injectors
> >quit around 1 ms. All of them draw about
> >.6 to .7 amps at 95% duty cycle.
> >Next step is plumb them up and measure the flow
> >as a function of pulse width and RPM. I still need
> >a few parts like a 50 psi fuel pressure gage which
> >I will order tomorrow from McMaster Carr.
> >
> >Paul Lamar
> > > Might I suggest an oil pressure gage.  I've had no problems using them,
> namely the same one for ~10 years.
> > Cheap & easy to get from your favorite auto part store.
> > Marc Pedings
> > Thanks for the tip Mark.
> > Paul Lamar
> > The next day. ---------------------------------
> > Got the system working. See the attached jpg. Found out a very interesting
> fact. The RX8 red injectors quit working at 1 ms and below if you up the
> fuel pressure much above 40 psi.  I set it up with 1.1 ms and 1800 RPM
> for an half hour at 40 psi and I got 75 ml. That is 150 ml per hour or about
> 4.8 ounces of fuel for both.  Lets see that is .01875 per injector
> or .0375 gallons for both, Since there are 6 pounds in each gallon
> that is .225 pounds. At .55 pounds per HP per hour that is less than
> about .4 HP. I doubt the engine will idle at .4 HP. What I saw on
> the dyno was about 10 HP at idle so these injectors are rather
> amazing. They are probably near useless for our purposes. I'll check
> the mid range shortly just to make sure. They have a nice foggy
> spray pattern however.  Check my arithmetic.
> > The return line had very few air bubbles in it and they were moving fast in
> a 3/8 ID return line so if you are not returning fuel to the tank you are drawing
> from, this system will empty that tank lickity split, mostly while you are
> taxiing out to take off. ALWAYS return the fuel to the tank you are
> sucking from. I don't know what the flow rate was yet but I will test it
> shortly. The MSD high pressure pump was drawing 8.75 amps at 12 volts.
> > I connected my auto parts store vacuum pump to the pressure regulator
> and discovered a slow leak. What this means is the regulator will
> not lower the pressure at part throttle (15 inches of Hg MAP) and
> your engine is likely to run too rich. Hopefully putting Teflon tape on
> the 1/8th pipe thread where the intake pressure goes into the regulator
> will fix the leak. If you are having problems with Tracy's EFI system
> this vacuum pump is a good investment to check for leaks in the
> vacuum system feeding Tracy's pressure sensors.
> > Also I consider a good aircraft manifold pressure gage a must.
> > BTW McMaster Carr has some cheap 2.2 inch diameter gages with 1% accuracy
> and silicone fluid filled for damping at about $15 dollars each. I am using
> the 60 psi version for monitoring the fuel pressure. Works great.
> > Paul Lamar

Hi Paul,

I have an Aeromotive fuel regulator.  In the instructions they
specifically caution against using hand vacuum pumps to test the
regulator.  They say a small leak is usual but claim it won't effect
normal operation with the engine vacuum.

Bob W.

Well maybe. I think they are talking about it in the context
of a mass air flow sensor. In our case, with Tracy's computer,
the correct manifold pressure is critical or you will not get
the proper mixture at part throttle. Since the fuel pressure
regulator vacuum plumbing is part of the sensor plumbing a leak
at the fuel pressure regulator vacuum line input will  definitely
cause problems.

What will compound the problem is the leak will cause the
fuel pressure regulator to not lower the fuel pressure as much as it
should. Since the fuel pressure is too high and the MAP sensors are
getting a higher manifold pressure reading than is justified by the
throttle position the engine will run rich on the low end which is
exactly what we were seeing on the dyno.

Is this clear or do we need more explanation or pictures? In other words
does everybody agree?

If the leak can't be fixed I suggest sending it back and getting another
brand that does not leak.

Bob, do you have a web site for Aermotive or a phone number for them?

Paul Lamar

Here is their web site.  http://www.aeromotiveinc.com/ and I have
attached a jpg of the instruciton page.  They have a pdf of the
instructions on the web site but it won't allow me to save a copy.

Bob W.