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Model Number 55501-c
Fuel Pressure Regulator
Operating and Installation Instructions
CCAAUUTTIIOONN!!
This product is to be installed only by persons knowledgeable in the repair and modification of vehicle fuel systems
and general vehicle systems modification. Only a qualified technician or mechanic who is aware of applicable
safety procedures should perform the installation of this product.
GASOLINE AND OTHER FUELS ARE FLAMMABLE AND CAN BE EXPLOSIVE!
Perform the installation in a well ventilated location only to minimize the build up of fuel vapors. NO open flames,
smoking or other sources of ignition are to be present duri ng installation, to prevent fire or explosion that can cause
serious injury or death. Grinding, cutting, and drilling must be performed with care to prevent ignition. Draining and
removal of all fuel and ventilation of vapors in vehicle and fuel system is recommended wh en performing such
procedures. Proper eye and personal protection is required at all times during installation.
WWAARRNNIINNGG!!
The Vehicle’s fuel system may be under pressure! Do not loosen any f uel connections until relieving all fuel system
pressure. Consult an applicable service manual for instructions to relieve fuel system pressure safely.
This product is intended for racing, off-road, or marine use only. This fuel system component is capable of altering
engine tuning and therefore not legal for sale or use on emission controll ed motor vehicles.
Product Contents:
Check the diagram and list of components
(right) to ensure that no components are
missing from box. Contact your Fuelab
distributor immediately for replacement.
55501-c Features and Performance Ratings:
Inlet Port Size -8AN Military Port
Outlet Port Sizes -8AN Military Port
Regulation Slope 0.8 PSI/GPM
Maximum Flow
Capacity
Pressure
Adjustment Range
160 GPH with 20 PSI Inlet
(600 LPH at 1.4 Bar Inlet)
Pressure Range “C”
4-12 PSID
(.3 – .8 Bar)
(3X) -908
O-rings
Jam Nut
Plug
(3X) Bracket Lock Washers
Flat Washer
Port Filter
(3X) Bracket
Screws
RegulatorAdjustment Screw
Bracket
Part of Regulator.
DO NOT LOOSEN
WARNING! Exceeding maximum inlet pressure (45 PSI) may result in an over-pressure operating condition.
Before Installation, Plan Entire Fuel System:
These instructions are limited to general topics of regulator component i nstallation and may not include specific
information pertaining to your application. These instructions are written assuming the use of an internally relieved
electric fuel pump with 45 PSIG maximum outlet pressure. Some high pressure pumps may be used with regulator,
but will require a bypass or relief, plumbed prior to inlet of regulator. This regulator has an internal spring that can
be changed for other pressure ranges, including “L” range, for 1-3 PSID and “T” range for 10-25 PSID, if required by
the specific application. Visit our company website for specific details pertaining to example fuel systems and other
solution ideas. Additional information including advanced troubleshooting, any speci al alerts and FAQ’ s pertaini ng
to this and other products is also available.
General Regulator Performance Notes:
The notation “PSIG” means pressure in Pounds per Square Inch (PSI) relative to the prevailing atmospheric
condition or outside air. This is referred to as Gauge P ressure. The not ation “PSID” means pressure in PSI relative
to another pressure source or called the Differential Pressure (rel ative to Pressure Reference Port in case of
pressure ratings). This regulator acts via restriction to control pressure (restricting fuel between inlet and outlet
ports). Only “blow-through” boosted applications for carbureted systems should have a line plumbed to the
pressure reference port. “Blow-through” applications will have limitations based on inlet fuel pressure and boost
pressure. The amount of pressure difference to expect with application of full throttle compared to idle (for naturally
aspirated engines) is a function of how much flow the engine is using (reference Regulation Slope, above for
calculations).
105020521-1, Rev A Sheet 1 of 4
Page 2
Plumbing Planning Notes:
Minimize plumbing restrictions between carburetor(s) and regulator for peak performan ce. Use –6 AN (3/8”) to
–10AN (5/8”) line as required per flow rate requirements of the vehicle’s engine and fuel pump. See company website for nitrous oxide use and alternate plumbing schematics. See diagram on next page as well as diagram below,
to identify the ports used on the regulator. Pressure is regulated by the regulator to the rest of the fuel system (from
outlet ports), by restricting flow through the inlet port. Plumb the Pressure Reference Port using a fitting (Not
Supplied) for “blow-through” carbureted applications only, “blow-through” means that a turbo or supercharger is
used to pressurize the carburetor(s). When this occurs, fuel pressure must be compensated by the change in float
bowl pressure. If motor is naturally aspirated (Normal carbureted application, with float bowl vented to atmosphere)
allow this port to vent to atmosphere, do not plug or plumb to any pressure source. Use of supplied port filter is
shown below. The fuel line used must handle high pressure. The use of fuel line such as stainless steel braided
line and “AN” style fitting connections is recommended. The fuel ports (one –8AN Inlet Port and two –8AN Outlet
Ports) use “AN” or “military” style fittings. This plumbing standard is commonly used with racing and high
performance applications. See step 6 on next page for additional information on this port standard. A fuel filter with
a 40 micron or lower particle rating is required to be used upstream of regulator and downstream from fuel pump to
protect it and the carburetor from foreign object damage. Reference the Schematic Diagram below for filter
locations. Use of a liquid filled gauge exposed to engine compartment heat is not recommended as the liquid inside
the gauge may exert measurement errors. DO NOT plumb gauge port to any gauge mounted insid e the vehicle or
in passenger compartment. A line burst can spill fuel inside passenger compartment and on occupants, possibly
causing serious injury or death. An electric gauge or pressure transducer system is recommended for readings in a
passenger compartment.
Typical Carbureted Fuel System Schematic Diagram:
Typical Dual Inlet
Carburetor Shown
Specifications and Recommendations.
55501-c Regulator
Installation Steps:
Follow Fuel Cell Manufacturer's
Recommendations for Proper
Vented Fuel Cell or Fuel Tank.
Tank must be Plumbed According
to Maximum Pump Flow Rate.
Consult Pump Manufacturer's
Fuel Straining Filter Required, Typical
75 Micron Filter Recommended. Straining
Consult Pump Manufacturer's Specifications.
Micron Rating: 75-150, Fuelab
Filter may be Installed in Fuel Pump,
Fuelab Prodigy 40402 Series
Fuel Pump Recommended.
Fuel Filter with 60 Micron or
Lower Particle Rating is Required.
Fuelab Filter with 6, 10 or 40
Micron Rating is Recommended.
Fuel Pump,
Cell Vent Plumbing
1. Disconnect the ground terminal from battery and allow the vehicle’s engine and exhaust system to cool.
Relieve fuel system per applicable service manual. Follow all Warnings and Cautions written on previous page
of these instructions.
2. Modify, remove or replace other fuel system components as required per establi shed build plan (reference
notes on previous page and above).
3. Use the supplied bracket as a drilling template to mark holes for mounting bracket. Choose a location that
minimizes exposure to excessive heat, near carburetor(s). Mounting bracket can be modified as required.
105020521-1, Rev A Sheet 2 of 4
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4. Apply light oil onto the threads of the Adjustment Screw. Thread the Adjustment Screw by hand until a slight
tension is felt, this position is the minimum pressure setting. Do not tighten screw any further. Pressure is to
be adjusted later in these instructions. Install the Flat Washer, then the Jam Nut. Tighten the Jam Nut hand
tight for later adjustment.
5. Install Bracket to regulator using supplied Bracket Screws and Bracket Lock Washers. Tighten Bracket Screws
between 25-40 in·oz of torque (snug, do not over tighten screws).
6. Install the fuel fittings (not supplied). The threads used on these Fuel Ports are not tapered or pipe threads.
Do not use Teflon
thread tape or thread sealant on these threads, as this can cause leakage or introduce
debris into the fuel system. Fittings to be used with these style of ports require use of the enclosed–906 O-
rings for proper sealing (reference diagrams, below). Use light oil to lubricate the O-rings just prior to
installation. Install the O-rings onto the fuel fitting first. Position the O-ring in the thread relief of the fitting as
shown in the diagram, below. Thread fitting into regulator and tighten between 5 and 15 ft·lbs of torque.
7. Use Teflon
tape or thread sealant on all 1/8”-NPT fittings to be used for the Gauge Port and Pressure
Reference Port (see diagrams, below). Install fittings or plug as required. If pressure reference port is not
plumbed, then install the Sintered Bronze Filter (supplied) and allow fitting to vent to atmosphere (do not plumb
or plug port). Use of Port Filter (only) does not require the use of Teflon
tape or thread sealant. For extra
level of safety, pressure reference port can be plumbed with float bowl vent, in case of rare diaphragm failure.
8. Install regulator assembly into vehicle, fastening the bracket to the vehicle. Attach fuel lines, Gauge Port line (if
external pressure gauge is used in application) and Pressure Reference Port line (if applicable). Boosted
applications (such as turbo or supercharger) will require a hose clamp on barbed fitting to prevent hose from
coming loose. Use of –3AN or –4AN fitting and line can also be used as a substitute to the barbed fitting.
Example -8AN
Fitting Shown
(Not Supplied)
Union
Install with Cup
toward Regulator
Front
(Logo)
Spring Guide Ball may appear to be Off-Center
Ajustment Screw Centers this Part upon Installation.
Gauge Port Plug
(can be substituted
for gauge or fitting)
Example -8AN
Union Fitting Shown
(Not Supplied)
Sintered Bronze
Filter Shown (can be
substituted with
other fitting)
1/8"NPT Pressure
Reference Port
(Vented to Atmoshere
for Naturally Aspireted)
Adjustment
Screw
Jam Nut
Flat Washer
Unique Serial
Number
Identification
Part of Regulator.
DO NOT LOOSEN
-908 O-ring
-908 O-ring Shown,
prior to Fitting
Installation
1/8"-NPT Gauge Port
-8AN Inlet Port
(45 PSI Maximum)
Example -8AN Union
Fitting Shown
(Not Supplied)
-8AN Outlet
Port (Same
for Both Sides)
(3X) Bracket
Lock Washer
(3X) Bracket Screw
9. Inspect fuel system for any contact of fuel lines or wires with other components that can cause chafing or
rubbing. Secure all components and fuel lines.
10. Connect the vehicle’s battery. If the float bowls of the carburetor are empty, then the fuel system can typically
be self-primed. If the float bowls are full, then fuel system may have trouble priming. One of the outlet fuel
lines can be used to purge system through fuel collector for initial priming. Start engine and fuel pump, while
monitoring fuel pressure. The pump will have to operate several seconds (60+) to prime and drive air out of the
fuel system. Fuel system pressure should read about 4-5 PSIG (use an external gauge for adjustment if a
permanent gauge is not used). Inspect vehicle for any leaks. Turn off fuel system and repair any leaks that
may be present before continuing.
11. When adjusting pressure, be sure that fuel pump and engine are operating to monitor pressure. Increase
pressure by rotating adjustment clockwise. Do not thread Adjustment Screw past jam nut within 1/8”. Over
tightening the adjustment screw can damage the regulator. For repeatable readings, en gine should be
operating normally at idle. If the fuel system is not flowing (such as engine running) then adjustment will be
difficult, especially when trying to lower fuel pressure.
12. After final adjustment of fuel pressure, to desired level, tighten Jam Nut. Road test vehicle, and retest pressure
upon return to ensure accurate adjustment.
105020521-1, Rev A Sheet 3 of 4
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LIMITED WARRANTY
FUELAB, a division of FCP, Inc.
62056, USA
Limited Warranty
1.
Manufacturer warrants that the Products sold hereunder will be free from defects in material and workmanship for a
period of 2 Years from the date of purchase to the original purchaser. If the Products do not conform to this Limited
Warranty during the warranty period (as herein above specified), Buyer shall notify Manufacturer in writing, or by
phone, of the claimed defects and demonstrate to Manufacturer satisfaction that said defects are covered by this
Limited Warranty. If the defects are properly reported to Manufacturer within the warranty period, and the defects
are of such type and nature as to be covered by this warranty, Manufacturer shall, at its own expense, furnish
replacement Products or, at Manufacturer's option, replacement parts for the defective Products. Removal of
Products from vehicle (
combustion engine. This product is
shipping to Manufacturer and installation of the replacement Products or replacement parts shall be at Buyer's
expense.
Other Limits
2.
THE FOREGOING IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. Manufacturer does not warrant against damages or defects arising out of improper or abnormal use or
handling of the Products; against defects or damages arising from improper installation (where installation is by
persons other than Manufacturer), against defects in products or components not manufactured by Manufacturer,
or against damages resulting from such non-Manufacturer made products or components. Manufacturer passes on
to Buyer the warranty it received (if any) from the maker thereof of such non-Manufacturer made products or
components. This warranty also does not apply to Products upon which repairs have been effected or attempted
by persons other than pursuant to written authorization by Manufacturer.
("Manufacturer") warrants its
.
Vehicle means any automotive, bike or marine transportation powered by an internal
.
, having its principal place of business at
FUELAB
intended or designed for use on aircraft, experimental or otherwise.),
NOT
products (the "Products") as follows:
826A Morton Court, Litchfield, IL
Exclusive Obligation
3.
THIS WARRANTY IS EXCLUSIVE. The sole and exclusive obligation of Manufacturer shall be to repair or replace
the defective Products in the manner and for the period provided above. Manufacturer shall not have any other
obligation with respect to the Products or any part thereof, whether based on contract, tort, strict liability or
otherwise. Under no circumstances, whether based on this Limited Warranty or otherwise, shall Manufacturer be
liable for incidental, special, or consequential damages.
Other Statements
4.
Manufacturer's employees, representatives' and/or resellers ORAL OR OTHER WRITTEN STATEMENTS DO NOT
CONSTITUTE WARRANTIES, shall not be relied upon by Buyer, and are not a part of the contract for sale or this
limited warrant y.
Entire Obligation
5.
This Limited Warranty states the entire obligation of Manufacturer with respect to the Products. If any part of this
Limited Warranty is determined to be void or illegal, the remainder shall remain in full force and effect.
Warranty Service
6.
What Does This Warranty Not Cover?
flood) is not covered. Also, consequential and incidental damages are not recoverable under this warranty. Some
states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or
exclusion may not apply to you.
How Do You Get Service?
Registration card, or register on-line at www.fuelab.com/warranty within 30 days of purchasing the Product.
If something goes wrong with your product contact FUELAB at 1-800-541-2345, International customers call 001-
217-324-3737, for a Return Authorization Number (RMA). After receiving your RMA send it postage paid, fully
insured, with a brief written description of the problem to:
.
.
.
Any problem that is caused by abuse, misuse, or an act of God (such as a
In order to be eligible for service under this warranty you
MUST
return the Warranty
FUELAB Warranty Department, 826A Morton Court, Litchfield, IL 62056
We will inspect your Product and contact you within 72 hours of receipt to give the results of our inspection and an
estimate of the labor and/or parts charges required to fix the Product, if applicable. If covered under this limited
warranty Manufacturer will repair Product and return it to you at no cost. If the Product is NOT covered under this
warranty and if you authorize repairs, we will return the repaired Product to you COD, or prepaid via credit card,
within 72 hours. There is no charge for inspection. If return product is found to be free of defects a $25.00 shipping
and handling charge will be applied. We will return the repaired Product to you COD, or prepaid via credit card,
within 72 hours.
105020521-1, Rev A Sheet 4 of 4
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