Implementation of the steps outlined here will
almost certainly trigger revocation of our tree-hugger status!
PART III—Electronic Fuel
Injectors, Selection and Installation
Always keep in mind that while no “high-performance”
version of this engine was built (even in the Land of Oz), Ford did intend
for it to be a highly reliable, high-economy, high-torque, bottom-of-the-line
truck engine, and therefore the design compromises made were conservative
in nature—want high-torque at low RPMs? Cylinder displacement! Want durability?
Seven main bearings and cam gear drive! Want cylinder block stiffness?
Thick castings throughout the head (you should see some of the outrageous
porting done on these heads--think sewer pipe). Want to make sure
your fleet driver can’t deliberately blow up an engine so he can get some
paid downtime? Use small, maxed-out fuel injectors on it, and camshaft
timing biased toward the low end (the stock cam runs out of breath promptly
at 4,000 rpm., but boy does it pull hard 1,800-3,000).
Assumptions, assuredly, but curiosity, observation,
deduction, trial-and-error, the various Internet forums, personal interaction,
initiative, and blind-melon assumptions are really the keys to effecting
performance increases from this engine, and since the engine was overbuilt
to begin with and skewed by the factory toward low-rpm torque production,
grafting on proven mild 5.0 V-8 hardware can yield astonishing results.
The trick is to enhance the stock midrange curves without losing bottom
end. Upgrading the fuel injection hardware is one of these, as are virtually
any exhaust improvements.
A fuel pressure guage is absolutely mandatory to this
project, as is an adjustable fuel pressure regulator and bigger injectors,
19-lb./hr. (or higher). Ford specified white plastic-topped weenie 12-lb./hr.
injectors @ 55-60 psig fuel pressure for the 300-EFI (4.9L) engine, whereas
the rest of the concurrent V-8, V-6, and I-4 truck engines ran orange plastic-topped
19-lb./hr. injectors @ 30-45psig.
Studly19-lb./hr injector (top)
Needs Viagra:12-lb./hr. injector (bottom)
All of these engines (except the 4.9L) had a crossflow cylinder head design, which places the fuel injectors a cylinder head’s width away from the hot exhaust manifold, enabling those injectors to run much cooler. The 4.9L has exhaust and intake ports all in a row on the same side of the cylinder head with the injectors in a very close proximity to the exhaust manifold, and may be subject to vapor lock when run at a lower fuel pressure, which was one of Ford’s criteria in designing this engine’s fuel system with a higher working pressure. One of our design criteria is the ability of this revised fuel system to pass emissions testing via a turned-down line pressure. The hellish Texas summertime approaches, so we’re sure to learn all about vapor lock.
The higher line pressure may in its turn have influenced the Ford designers to specify a 12-lb./hr. rated fuel injector rather than the other truck engines’ norm of 19-lb./hr., and with that 7-lb./hr. difference lies the crux of this upgrade, because the pathetic 12# units are being replaced with the 19# (or higher) units. There is some speculation that 24-lb./hr. injectors may also be of value because of their additional capacity to supply ultimate fuel quantity for very high horsepower engines, as the later (’95 California/’96 50-state) Mass Air Flow (MAF) 4.9L units are adaptable to higher flow values achievable. Supercharging, for instance.
The ’87-’95 50-state speed density versions generate error codes (the “check engine” emissions dash light) at a relatively low circa-40 psig, (Ford averages 39 psi across their lineup), but this is still a very worthwhile swap. Apparently, the antiknock sensor allows the engine to run a lot of ignition advance because the rich fuel mixture simply won’t spark knock, which on these horribly lean low-emissions/high-MPG engines makes an incredible difference in their power output and drivability. We are having very good luck with our initial advance increased to 12-degrees BTDC; stock is 10 BTDC, and we’re burning that wonderful 87 octane stuff. We’ve mused aloud about the possibility of using higher octane and cranking the advance way up there and been told sternly to “…not trust…” a knock sensor too far.
We went about guage-mounting the “harder” way (as opposed the “hardest” way, which means interior-mount…cleanly…fooling around under the dashboard…) and built a neato-looking, cheapo engine compartment guage mounting manifold which included a Schrader valve for depressurizing the fuel system (like stock).
These are the parts we used:
View of assembled guage manifold
--4 Stainless steel hose, 1/16” MNPT x –4 flare
adaptor, pressure takeoff port on fuel rail at extreme rear of engine,
between firewall and head at #6 ram tube
Measure the total length of the two pipe plugs, and
transfer that measurement LESS 1/16-inch (or so) to the 10-32 drill bit.
Wrap a length of tape around that drill bit at this measurement so that
maximum depth is marked and easily seen and is achieved without perforating
the plug…gasoline under high pressure will be contained within the guage
manifold and back behind these not-completely-drilled-through plugs! Tap
each pipe plug 10-32, as far as possible. Thread into the bulls of the
two tees having a vertical orientation.
Cut a straight length of light-guage metal angle 1”
tall, 1” wide, and 6” long. On its back (or vertically-oriented) side,
this angle will mount to the firewall, and the bottom (horizontal-orientation)
will form a surface to which the fuel guage manifold is anchored.
Measure exactly the mean distance between the pipe
plugs, and transfer that measurement to the horizontal mounting “shelf”
formed by the angle, so that the fuel guage manifold is centered in both
the length and width of the angle. Drill those holes ¼-in. dia.
Shorten the two 10-32 screws so they bottom out in
the pipe plugs using one flat washer each, but not the angle. The added
thickness of the angle when assembled will ensure proper torque without
thread-bind at final assembly time.
Mock-up the fuel guage manifold on the bracket, and
mark the back of the bracket for holes for the two #10 sheet-metal screws
that that will fasten the assembly to the firewall, keeping in mind that
a screwdriver has to be held nearly horizontal to turn the screws, then
drill those holes, too.
Countersink all holes, finish all edges, clean in
lacquer thinner, and, if galvanized, smear on some cheapo 5% white vinegar,
which will etch the surface and enhance paint adhesion, ‘cause it’s time
go go blow some paint on the angle, the four screwheads, and the guage
manifold (plug the two end holes and center guage hole with toilet paper,
masking tape if you’re a high-roller). We used ‘60’s Ford engine blue.
Final-assemble the guage manifold to the angle, using
copious amounts of the threadlocker plus one flat washer per screw. Remember
how those four ¼-in. dia. holes were bigger than the 10-32 but smaller
than the o.d. of the washers? Gee, it all went together easily! (If
can drill same-size accurately-spaced holes, well…)
You’ve been itching to do this one…go ahead and screw
that new, chromed and high-perfed-logo guage in—WITH THE CORRECT OPEN-ENDED
WRENCH ON THE WRENCH-SQUARE AT THE BACK OF THE GUAGE, not with pliers around
the periphery of the guage case! It is only too easy to ruin a delicate
guage, so don’t get ham-fisted (drink decaf coffee, not beer); NPT means
“National Pipe Taper” meaning the shank of an NPT nipple is gradually tapered,
wedge-shaped in profile, and gets progressively tighter as it is screwed
inward. The mounting spud of this guage, like most of the rest of the assembly,
is 1/8” NPT brass; some judgement , “feel”, is required to get a., enough
torque without too much torque on this guage fitting, and b., correct orientation
of the guage’s face so that the numbers midpoint of its travel are in the
12 o’clockpoint position; i.e., “50” psi should read at the top of a 0-100
guage; “30” psi likewise in a 0-60 piece.
A vertical-mount guage could be used, but to our mind
the assembled guage manifold unit is too tall, and takes up too much firewall
Using the correct backup combination of box end and
line wrenches and being very careful not to disturb the 90-degree difference
in all the tee’s orientation, assemble the Schrader valve to the driver’s
side end tee’s run, and the 1/8” x –4 flare to the passenger’s.
Relieve pressure on the engine’s fuel rail via the
stock Schrader valve—conveniently located near #6 cylinder, nestled inside
the curve formed by the EFI air manifold tubes, close to the firewall.
Try not to spew gas everywhere; self-immolation went out with the ‘60’s—try
not to reinvent a questionable fad! Catch any pressurized gas with a rag
(and then dispose of it, muy pronto!) As always when working on a fuel
system, have a fire extinguisher close to hand.
Unscrew the stock Schrader, and screw in the
special Ford-size flare fitting, snugly but not excessively tight—those
threads are small! We used no Teflon tape here. Dispose of that Schrader;
it won’t fit anything else, anywhere.
Hand-tighten the braided hose so that it will swivel
freely without coming off fuel rail fitting, and gently, thoughtfully,
route it through the air manifold between runners #5 and 6, then up and
backwards outside the heater core box, then curve around so the other end
swivel fitting is aligned horizontally at the firewall, pointing toward
the spark plug side of the engine.
Loosely screw the hose to the guage manifold, align that puppy so it is horizontal and high enough on the firewall to be easily seen, fasten the bracket-to-firewall screws, and using two wrenches, tighten the swivel fittings, then leak test your work by turning the ignition key to “On” but not “Start” (you can hear the in-tank pumps pressurizing the system). Leaving it “On”, go eyeball your pipe joints, then test with a dry finger, NOT A LIT MATCH!
We suppose it’s possible to change regulators without removing the upper air manifold and appurtenances, but we unlucky enough to be hatched without the eight fingers for each of three or four hands jointed by quadruplicate elbows required, so we pulled the upper manifold. Begin by pulling off the air cleaner tubes, throttle body, EGR from T/B, and that upper air manifold. Clean that mating flange well, and when pulling that upper manifold, pull straight up! There are a couple of easily-broken plastic dowel pins locating gasket and manifold.
Also, the Thermactor (you know: air pump, smog pump, @#$%^&*() pump, etc.) vacuum and pressure connections and numerous other vacuum connections will have to be disconnected.
Ford Motor Company, in its infinite wisdom, has equipped modern vehicles with numerous vacuum-operated emissions devices, fed through 1/8 dia. plastic hoses often bundled together and/or in with wiring harnesses.
These small plastic vacuum pipes embrittle with heat,
oily vapor, and time (obviously; they belong in a long-lasting motor vehicle,
right?) and therefore, when disturbed, break with only the smallest provocation.
Only seriously disturbed citizens soup up their six-cylinder pickups, so
plan on using up some of that copper line and 1/8 i.d. rubber hose you
were told to go get. Or don’t.
Upper manifold off (that last bolt by the firewall
was a “challenge”, wasn’t it?), get the that Allen wrench, remove and fling
stock regulator and weirdo allen bolts in the trash, where they belong.
Rip your cool new adjustable unit out of its blister
packaging with the Crane Cams logo (on the packaging, not the regulator…somebody
else makes it, Crane just markets it--cheaply), and plug it into the fuel
rail. We’re using the Crane Cams piece because the vacuum reference hose
slides down over the pressure adjusting screw, which has a small hole drilled
in it. The hose hides the fact that it is adjustable, which to our paranoid
mind is a Good Thing come emissions inspection time.(PHOTO 6)This
is not such a Good Thing if you want to make adjustments with the engine
running and vacuum reference hose connected, and there are other AFRs out
there with a separate vacuum nipple.
The good news is, the pressure and return spuds and base gasket all match up perfectly, same-same, which is what really matters.
The bad news is, the new regulator’s base flange is
smaller, shaped differently, has a way-different bolt pattern, and the
flange is internally-threaded so its hold-down screws thread from the bottom
upwards through an unthreaded fuel rail mounting pad, whereas the I-6 fuel
rail mounting pad is internally threaded, and the stock regulator’s mounting
flange is undrilled, the screws threading downward.
A retroactive review of “Ford Electronic Fuel Injection
Systems” confirmed this—all the pictures of different I-4, V-6, and V-8
engines used the bottom-upward bolting system.
We know that you really wanted to know that.
The 4.9L fuel rail regulator base is much larger physically
that the 5.0L AFR, so it would be possible to simply drill and tap two
new holes (of three required) in the 4.9L fuel rail’s regulator mounting
pad. This leaves the third mounting hole in the new regulator hanging off
in space, with nothing to secure it to—and since the base is triangular,
all three mounting holes have to be used to ensure an equal clamp load.
We suppose that we could have devised some sort of clamping strap to pass
underneath the fuel rail, but that’s tacky and besides, we’d have to drill
and tap two additional holes in that mounting pad--and we really don’t
like the idea of drilling holes that closely to the fuel rail inlet; microscopic
metal shavings have a way of migrating into fuel injectors!
We elected to do something simpler, cleaner, and far
The regulator is barrel-shaped, the two halves crimped
together circumferentially at the widest part of the “barrel”, a perfect
place for a hold-down flange.
Circumferential crimp ring around body of fuel pressure
regulator; large washer illustrating hold-down collar flange principle
Large triangular base of stock regulator showing intake and return spuds, gasket, unthreaded mounting holes
Note different mounting flanges, mounting method, vacuum reference elbow, 1.5” hole in center of 3” dia. flange—the pressure adjusting screw has a small hole drilled through its middle, 19-lb./hr. injectors, all in a line, hold-down flange. Partially obscuring injector #1 is the infamous #1 fuel rail bracket that didn’t get adequately tightened! Look carefully and you’ll note we were living dangerously in this picture and weren’t at that time using Nyloc backup nuts underneath hold-down screws!
The idea is go buy a 4” by 4” hunk of .125” thick
mild steel plate. The thickness, material, and size really doesn’t matter
as long as it is inflexible and can take a 3-inch outer diameter cut.
The first step is to lay out what is essentially a
big, flat, washer with three ¼” dia. holes in it that correspond
to the threaded holes in the regulator’s mounting pad on the fuel rail,
and drill them.
The second step is to is to holesaw the 1-1/2” central
hole which will slide easily but snugly over the new AFPR.
The third step is to make the 3” outer holesaw cut,
at which point the rough-in work is done. Go countersink, deburr, and paint
your new masterpiece of machine art.
Paint dry, mount the flange using all the #10-32 machine
screw hardware mentioned above, with plenty of Loctite. The factory holes
probably have metric threading, but the #10-32s screw in there though just
a smidge looser than is ideal. The threadlocking compound and the Nyloc
backup nuts make that irrelevant.
This is a no-brainer; you can’t screw it up (we did,
naturally!) All six injectors seat (float, actually) in drilled pockets
in the lower air manifold, sealed by thick “O”-rings, tips pointing at
the respective intake valve, and are held in place from above by the fuel
rail, which in its turn is bolted to the same air manifold by THREE bolts.
Remove the bolts, and gently work the fuel
rail off the injectors. There is enough play in the fuel delivery and return
lines to make this possible without disconnecting the A/C-type garter fittings
back by the firewall, which is a major PITA. Unhook the Weatherpack electrical
connectors (oh-so-gently; the plastic clips love to break).
Pull the old injectors from both air manifold
and fuel rail, clean fuel rail and air manifold injector pockets, lightly
lube all new “O”-rings and all pockets, and gently work the injectors
into their respective manifold pockets and the fuel rail onto them.
Reinstall all three bolts, torque all three bolts to 18-ft./lbs; read that last sentence again.
Take a good look at the fuel rail mounting bracket
in the vicinity of injector #1, just beyond the 180-degree curve taken
back toward the firewall by the fuel rail. Certain brainless wonders left
that bolt loose. Consequently, the slight freeplay allowed between bracket
and mounting pad by that oversight enabled gasoline pressurized at 55 psig
to spit the upper “O”-ring out after a couple of days, and spew gasoline
so hard into the windings of the alternator that it shorted out temporarily,
scaring us somewhat.
In fact, down here in Texas, they call that kind of
scare a “brown pants special” or “trouser chili”.
Tighten. You have been warned.