Fuel Injection Pump Assembly

I was very fortunate to meet a new EAA chapter member Scott (last name left off to protect the innocent). Scott is a local large carrier A&P mechanic, Master Tuber (hydraulics and fuel lines bender extraordinaire) , and lives a stone throws distance from me.  Scott is contemplating building an RV and recently came by to take a look at this little project of mine. Well don't look now, but he was put to work instantly, helping me figure out how to plumb all these lines associated with the fuel injection pump.

Here he holds the special fuel filter that need to go before the pump. Don't ask me what he was doing with it. "It's a Master Tuber thing," he said. At any rate, he found the whole soft aluminum tubing thing unacceptable and began running stainless steel lines and such, kindly donated from that unnamed commercial carrier. 

Here sits the electric boost pump and filter assy. located forward of the spar. Quite a rig he made. No way I could have done that. Nice pretty bends, cool fittings, and all in a small package.

Many thanks Scott!!


Update 4/27/03. I received this e-mail from AFP.

I was alerted to your web site by one of my employees.  Seems you had
some issues installing the fuel injection system.  After reviewing the
contents of your web site, I must say, if we spent as much time on such a
detailed site as this, we'd not have time to produce one single part. 
Everyone's good at something as the saying goes.

Since I'm sure you have a lot of RV builders visiting your site, and in
the interest of getting facts straight, we would like to add a few comments
that may be helpful to other builders. Seeing as you have a interest in
web design, maybe you can add these comments as an amendment to your
installation section.

1.  We don't see that cutting out a notch on the mixture control cable
bracket for clearance of the nose gear strut on a "RV-A" is "major
gouging and fitting".  In fact the installation manual states there may be
clearance issues with certain installations that will require
modifications of the brackets.  This shouldn't be a big deal if you can build your
own airplane.  Having common parts that the customer can easily modify
keeps the kit price from getting out of sight.
2. As for your friend, the Master Tube Bender/A&P.  What he does with
stainless tubing is his business.   But for the sake of saving weight,
the tubing supplied on our pump package is MIL spec 5051-O seamless
material.  The working pressure of this size tube and wall thickness
will easily handle 1000 PSI.  That's a safety factor of 33. This type of
tubing should be used in the aircraft on the cabin side of the fire wall.  Why
add a bunch of unnecessary weight if you don't need to.  Did he use
stainless fittings, B-nuts and Sleeves too? (yes)  If not you can get into a corrosion
issue due to dissimilar metal contact.  In his defence, the pump/filter
package looks nice.
3. Maybe the filter box would have fit without modification if you had
read the instruction manual.  The Airbox mount plate goes on first, then the
Approach Clamp Ring.  This would have raised the filter box about 1
inch.  The complete assembly was engineered to fit in exactly the same
space as a carburetor.  The approach clamp ring should be inside the
box.  This gives the fuel control a nice smooth entrance for the air to
enter.  What you have now is a sharp corner that the air goes over
creating turbulence.  In the correct installation it puts the air box plate
mounting bolts on the outside of the box.  This keeps hardware from being sucked
up in the engine if a bolt and washer falls out. (They are correct. I did mount it incorrectly.

But i used platenuts so as to not loose parts in engine)
4.  It looks like the fuel system was made way more complicated than it
needed to be.  All those blue manifolds with solid tubing attached
looks confusing to me.  What are you doing here?  There should be no solid
tubing on the engine side of the fire wall.  This is another way for heat to
transfer into the fuel.  A #6 bulkhead fitting should come through the
fire wall.  A #6 firesleeved hose is run from there to the inlet of the
engine driven pump.  A tee fitting with a restrictor in the tee is attached to
the outlet of the engine driven pump.  #3 or #4 hose is run back to the
fuel pressure transducer from the restricted tee.  On the other end of the
tee, a #6 (supplied in the kit) firesleeved hose is run to the inlet of the
fuel control.  A #4 fire sleeved hose (supplied in the kit) runs from the
metered fuel outlet on the fuel control to the purge valve inlet on the
top of the engine.  It is routed through the cyl #1 and #3 lower cylinder
baffle.  The flow transducer should be in this line.  Because of the
transducer's light weight, you can support the hose to hold the
transducer.  This keeps engine vibration from beating up the flow
transducer.  There is no way to screw up the inlet hose and outlet hose
because they are  different sizes, and this keeps the length of hose in
the engine compartment to a minimum. (They are correct, except I have other items in-line)

An impressive web site though. (thanks)

Don Rivera
Airflow Performance, Inc
Phone:  864-576-4512
Fax:      864-576-0201
email:  airflow2@bellsouth.net

Last updated 04/28/2003