Mallory 5250 User manual

COMP PUMP®SERIES 250
ELECTRIC FUEL PUMP
PART NOS. 5250 AND 5250A
INSTALLATION INSTRUCTIONS
FORM 1038 (REV. F) 11/04
GENERAL INFORMATION
The COMP PUMP®250 Series Electric Fuel Pump is a high
volume fuel pump designed for serious racing applications.
The pump is factory set to approximately 15 PSI. In all
cases, this fuel pump must be used with a fuel pressure
regulator. We recommend the following:
Standard Regulator
Mallory 4 Port Regulator Part No. 4200 (gasoline)
Part No. 4201 (alcohol)
Return Style Regulator
Mallory 5 Port Regulator Part No. 4300M (gasoline)
Part No. 4301M (alcohol)
This fuel system must have a fuel return line going to the fuel
tank. We recommend at minimum a #8 AN (1/2") line.
If you use a standard fuel pressure regulator, not a return
style, run the fuel return line from the fuel pump’s fuel return
port. Use the 3/4"-16 thread x #8 AN flare fitting provided to
connect your #8 AN line.
If you use a return style fuel pressure regulator, run a #10 AN
fuel return line from the fuel pressure regulator’s fuel return
port and install a 3/4"-16 thread plug and o-ring in the fuel
pump’s fuel return port. You can find a 3/4"-16 thread plug
at most hardware stores. Do not try to adjust the bypass
adjustment - pump damage may result.
Be sure to install a suitable fuel filter (maximum 100 micron)
between the fuel tank and the fuel pump. Mallory COMP
FILTER®Series Part Nos. 3140 or 3500 are recommended.
This prevents debris from becoming wedged in the fuel
pump’s Gerotor and locking it. An additional filter(s)
(maximum 40 micron) should be installed just before
the carb(s).
PARTS INCLUDED IN THIS KIT:
1 COMP PUMP®Series 250 Electric Fuel Pump
3 Fittings, 3/4" - 16 x #8 AN Flare
3 O-rings, Nitrile 0.644ID x 0.087 thickness
NOTE: DO NOT OPERATE THIS PUMP
WITHOUT FUEL EXCEPT FOR BRIEF
PERIODS WHILE PRIMING
SPECIFICATIONS
Maximum recommended operating pressure: 20 PSI
(factory set at approximately 15 PSI)
Maximum dry suction lift: 3 feet. This is maximum distance
above the fuel level in the fuel tank that the fuel pump will
prime itself.
Oil pressure switch rating: 15 AMP
Fuel pump over current protection: 15 AMP fuse
Fuel application: Part No. 5250, Gasoline; Part No. 5250A,
Alcohol / Methanol
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CARB
FUEL
FILTER
REGULATOR
FUEL
PUMP
FUEL RETURN
FUEL RETURN
PORT FUEL FILTER
FUEL
TANK
FIGURE 1
FIGURE 2
FIGURE 3
MOUNTING PROCEDURE
Step 1
Mount the pump as close as possible to the fuel tank in a
well ventilated area with minimal exposure to road debris.
Avoid exposing the pump and fuel lines to moving parts
and hot surfaces, such as the exhaust system.
The pump should be mounted at tank level or below.
NOTE: Increasing distance between pump and tank will
decrease pump efficiency.
Step 2
Using the pump mounting bracket as a template, locate
mounting holes on a solid member, such as the vehicle
chassis. Drill clearance holes for 5/16" bolts. NOTE: To
ensure against a potential fire hazard from pump
flooding, mount the pump in a vertical position with
the motor on top.
See Figure 1.
Step 3
To prolong pump life and efficiency, a high volume fuel filter
such as the Mallory COMP FILTER®Series 500 Fuel Filter
(Part No. 3500) must be installed between the pump and
fuel tank. Connect #8 AN fuel lines as shown in Figure 2 for
Standard Regulator or #10 AN lines as shown in Figure 3
for Return (Bypass) Style Regulator.
Step 4
Be sure to install one of the Mallory High Volume Fuel
Pressure Regulators between the pump and carburetor.
For maximum efficiency, mount the pressure regulator
as close as possible to the carburetor. See instructions
packaged with the pressure regulator. Make sure all
fittings are tight so that air cannot enter the system.
(WITH STANDARD FUEL PRESSURE REGULATOR)
(WITH REGULAR STYLE FUEL PRESSURE REGULATOR)
FUEL OUTLET
3/4" - 16 (#8AN)
FUEL INLET
3/4" - 16 (#8AN)
FUEL RETURN 3/4" - 16
(MUST BE PLUGGED
WHEN USING A RETURN
[BYPASS] STYLE
REGULATOR
NITRILE O-RING
NITRILE O-RING
BYPASS ADJUSTMENT
NOTE: Bypass pressure above
20 psi will make the pump draw
more current and significantly
reduce pump life.
RED (+)
BLACK (–)
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IGNITION SWITCH
OIL PRESSURE SWITCH
TO ACCESSORIES
TO COIL (+)
GROUND
GROUND
COMMON
FUSE (15 AMP)
NORMALLY
OPEN
NORMALLY
CLOSED
FROM
VEHICLE
BATTERY
STARTER
VEHICLE
BATTERY
FUEL
PUMP
RED (+) BLACK (-)
FIGURE 5
FIGURE 4
IGNITION SWITCH
TO ACCESSORIES
TO COIL (+)
FROM
VEHICLE
BATTERY
GROUND
FUSE (15 AMP)
FUEL
PUMP
RED (+) BLACK (-)
WIRING PROCEDURE
Wiring the pump to an oil pressure switch provides power
only when the ignition switch is on and the engine is
running. This prevents the pump from running if your
engine stalls. Use 12 gauge wire or larger and be sure to
disconnect the battery ground cable before wiring the
pump. Refer to Figure 4 when connecting the pump to
an oil pressure switch.
The pump may be wired directly to the ignition switch “ON”
terminal and grounded to the frame or battery. Refer to
Figure 5 when connecting the pump to the ignition switch
“ON” terminal.
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FIGURE 6
18
19
20
21
22
23
24
9
10
11
14
15
16
17
12
13
1
2
3
4
5
6
78
MAINTENANCE –
PUMP DISASSEMBLY
If your pump fails to produce adequate pressure or
volume, it may require cleaning. Follow the steps below to
disassemble and clean your Mallory Electric Fuel Pump.
Refer to Figure 6 while performing the following steps.
Step 1
Remove the pump from the vehicle and clean pump exterior.
Place the pump on its side on a clean work surface. Scribe
or draw a line across the pump housing, port plate and fuel
chamber so that you can reassemble the pump correctly.
Step 2
Remove the two fuel chamber screws from the bottom of the
pump. Remove fuel chamber and port plate from the pump.
NOTE: Do not drop the gerotor from the pump cavity.
Step 3
Place your hand beneath the gerotor and hold the pump in
an upright position. The gerotor should slide out of the
pump and into your hand.
Step 4
To disassemble the fuel chamber, first remove the lock nut
and adjusting screw, then turn the fuel chamber over so that
the diaphragm spring falls into your hand. Remove the four
screws holding the diaphragm cap to the fuel chamber.
Remove the diaphragm cap, diaphragm, and damper spring
from the fuel chamber.
Step 5
Clean the gerotor and reinstall it in the pump housing.
Inspect the O-ring and gasket, and replace them if
necessary. Inspect the diaphragm for any small tears or
bubbles in the surface, and replace it if necessary. Inspect
the gerotor housing and port plate for wear. If the generator
has worn through the plating, return the pump to Mallory
for repair.
Step 6
Assemble the pump in the reverse order that you
disassembled it. Test bypass pressure. Adjust bypass
so that pump is producing between 13 and 20 psi.
1. JAM NUT
2. ADJUSTING SCREW
*3. PRESSURE ADJUSTMENT SPRING
*4. CAP SCREW (4)
5. REGULATOR CAP
*6. GASOLINE DIAPHRAGM
ALCOHOL/METHANOL DIAPHRAGM
*7. FUEL CHAMBER SCREW
*8. DAMPER SPRING
9. FUEL CHAMBER
*10. FUEL CHAMBER GASKET
11. PORT PLATE
12. GEROTOR
*13. GEROTOR BUSHING KEY
*14. GEROTOR BUSHING
*15. O-RING
16. GEROTOR HOUSING
*17. SEAL
*18. BRACKET VIBRATION GASKET
19. BRACKET
20. MOTOR HOUSING NUT (2)
21. MOTOR ADAPTER
22. SPRING WASHER
23. MOTOR ADAPTER SCREW (2)
24. MOTOR
*THESE PARTS ARE INCLUDED IN SEAL / DIAPHRAGM KITS
PART NO. 3171 FOR GASOLINE
PART NO. 3172 FOR ALCOHOL
IMPORTANT: Turn fuel chamber screws by hand until they
contact the chamber. Then torque to 24 inch/pounds
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ELECTRIC FUEL PUMP
TROUBLESHOOTING GUIDE
The following pertains primarily to Mallory COMP Pumps
equipped with Gerotor style pump systems, but also
applies to many other fuel systems.
BASIC INFORMATION
TheMalloryGerotorstyleCOMPPumpsaremoreforgiving
than vane style pumps, but it is still important to insure
they are properly mounted and receive clean fuel.
The correct mounting position is even with or below the
tank and preferably behind or next to the fuel tank. All
electric pumps push fuel far better than they can pull
(suck) fuel.
Make sure that a low restriction filter is between the tank
and the pump. A 40-micron element it sufficient to pro-
tect the pump from contamination such as dirt, rust, fuel
cell foam, etc. Mallory has them available that will screw
directly into the pump itself.
Electricpumpsneedacleanandstablepowersource. Run
a minimum of 12 gauge wires to the pump if it is relatively
close to the power source. Longer runs should utilize 10
gauge wire instead. With a trunk-mounted battery, we
recommend that you use a relay to allow for short power
wires to be run. Do not pull power from a common termi-
nal, especially if the
ignition is wired to the same terminal.
The regulator used must be properly matched to the flow
characteristicsof thefuel pump. Referto thecompatibility
information in the current Mallory Catalog. Small regula-
tors and big pumps don’t work. Also, check to make sure
the pump and regulator are designed for the type of fuel
that is going to be used.
For the longest possible life from your Mallory or
any other brand of electric fuel pump, it is highly
recommended that you use a bypass style regulator.
This allows the pump to run cooler, keeps the fuel cooler
reducing the chance of vapor lock, draw less amperage,
and supply constant flow of fuel. The minor inconve-
nience that running a return line to the tank presents is
more than offset by the positives mentioned above.
Fuel line size is based on the length of the lines in
addition to the intended use. The supply line to the
engine is based on the horsepower of the engine. The
return line size is based on the total volume of the fuel
pump. Basically, to insure stable fuel pressure, the
return line should be of sufficient diameter to handle
the full volume of the fuel pump without the engine
running. That means that the return should be as big
or bigger than the supply line.
Use liquid thread sealing or a suitable pipe dope and
not thread sealing tape on all threaded fuel systems
connections. Pieces of the tape can break off as they
are being assembled and plug up lines, get stuck on
small passages, and even seize up a pump if they are
large enough.
Don’t buy cheap fittings. Use low restriction fittings, pref-
erably CNC machined ones like those listed in the Mallory
catalog. Tightly angled fittings can be just as bad of a
restriction as too small of a line size. The larger the radius,
the better and make sure that you buy quality fuel lines.
Look at them closely and make sure they have a large
inside diameter. That especially applies to some of the
low cost dual feed lines being sold today. Some 3/8” OD
lines are 1/4” or less ID.
FREQUENTLY ASKED QUESTIONS
Q.- Why can’t I adjust my fuel pressure down? Even with
the adjuster backed all of the way out, I still have too
much.
A.- Start by checking to make sure the regulator is suit-
able for the pump you have installed. Next, if it is a
bypass system, check the return line size. If the return
line is too small, the regulator isn’t causing the pres-
sure, rather it’s the return line size is too small. This
is especially a problem when the factory return line is
used. Ford Mustangs are probably the most common
offenders.
There are a couple ways to prove it. The easiest way is
to remove the spring from the regulator. Without start-
ing the engine, turn on the pump. The pressure gauge
must read less than 3 PSI on a carburetor-equipped
engine and less than 10 PSI with high-pressure fuel
injection.
Q.- When I first hit the throttle hard, the pressure drops
then comes back up. Why?
A.- The pump has to catch up to the demand. The
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problem would not exist if the car had a return
(bypass) style regulator. The fuel would always
be flowing.
Q.- WhenIadjustthefuelpressure,it’sfinewhenit’scold,
but then it starts dropping off. If I let it cool off, the
pressure comes back up. If I readjust it hot, then I
have too much pressure cold. What’s going on?
A.- This is a classic problem when there is a liquid filled
gauge mounted on or near the engine. The pressure
isn’t changing, it’s the gauge reacting to the under-
hood temperature. To prove it, start the engine with
everything cold, then blow hot air from a hair dryer on
the gauge. You can watch the pressure reading drop.
It’s just the nature of liquid filled gauges and hot
engines. Try to mount the gauge away from as much
engine heat as possible.
Q.- I want to run a return style system, but there isn’t
another hole in the tank. What can I do short of weld-
ing in a fitting. Can I dump it back into the feed line?
A.- Run the return into the fill neck if you have to, but you
cannot either put it into the feed line or the bottom of
the tank. Remember to keep the return line above the
fuel level in the tank.
Q.- Every Spring, I have to take apart my pump and regu-
lator apart. I store my car in the winter in a garage.
Why the sticky mess?
A.- The higher octane the gas, the quicker it
evaporates. If you leave fuel in the system, add one
of the many additives available and put in a regular
pump gas. Racing type gasoline
evaporates quickly and leaves a sticky mess that will
gum up everything. Just remember to put the right
fuel in before you go out and stand on
the throttle.
Q.- I took my pump apart, cleaned it up and tighten it
back up. Now it doesn’t want to run. What did I do
wrong?
A.- When you put the pump assembly back on the bot-
tom of the motor, be sure to draw both of the screws
up slowly and evenly. Do not over tighten them.
Make sure all of the pieces go back on the same way
they came off. Putting a grease pencil mark down the
side of the pump housing is the simple way to make
sure that you don’t put it together backwards. They’ll
fit, but they won’t flow the fuel right.
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