The Fuel Pressure Regulator Damper (FPR-D) combines essential fuel system components into a high-flow package. It serves as a fully functional, high-performance adjustable EFI fuel pressure regulator with an integrated fuel pulse damper, making it suitable for any EFI fuel system.

The fuel pulse damper effectively smooths out "noisy" fuel systems that experience pulsing from the injectors and fuel pump.

Now available with a green anodized adjustment knob.

MOUNTING

This regulator features two M6x1mm threaded mounting holes. A laser-cut anodized aluminum mounting plate is included with four countersink M6x1mm bolts and nuts. The FPRD-RA can be mounted in any orientation, including upside down.

PLUMBING

The inlet (side) and outlet (bottom) have large 10AN ORB (7/8'-14) threaded ports. Two -6AN and two -8AN male adapter fittings are included to accommodate most aftermarket fuel systems. The 1/8' NPT auxiliary port can be used for monitoring fuel pressure, commonly with a Radium fuel pressure gauge. An included plug is available if this port is not utilized.

NOTE: This regulator has a single inlet port and a single outlet (return) port, making it unsuitable for dead-head fuel systems. It must be plumbed after the fuel rail. For dead-head fuel plumbing, refer to the Multi-Port Regulator (MPR).

FUEL PULSE DAMPER

The integrated fuel pulse damper stabilizes fuel pressure against pulses from the fuel pump, injectors, and regulator. Maximum damping efficiency is achieved at a base pressure of 40-105psi (2.8-7.2bar). This range refers to static pressure only. For dynamic fuel pressure outside this range, a vacuum/boost reference line is required for the damper; otherwise, this reference is typically plugged.

NOTES:

1. Base pressure is measured with the fuel pump running and without a vacuum line connected to the regulator.
2. This product is NOT FOR USE on the low-pressure side of mechanical fuel pumps, including direct injection HPFP.

• Minimum Pressure: 18.5psi (1.3bar)
• Maximum Pressure: 100+ psi*

*Maximum pressure is dependent on the relief valve inside the pump or the maximum current allowed by the fuel pump controller.

ABOUT FUEL PRESSURE DROP AFTER SHUTOFF

Some installations may experience a rapid drop in fuel pressure when the engine or fuel pump shuts off. This is considered normal for aftermarket fuel pressure regulators, regardless of brand. This can occur due to the diaphragm seat and return orifice not fully sealing when fuel flow stops. To regulate high fuel flow rates, the size of these components must be increased, which can prevent a perfect seal. This is not indicative of an issue or defect and does not require technical support. Fuel pressure will reset immediately when the fuel pump is activated again.

If the engine experiences symptoms such as long cranking to start or delays in pressure building, these issues are likely unrelated to the regulator and may indicate a problem with the fuel feed hose draining back to the tank, possibly due to an internal leak in the pump module or the absence of a fuel pump check valve.

1:1 RISING RATE VACUUM REFERENCE

RA-series regulators feature a 360-degree swiveling vacuum reference port that is double O-ring sealed, allowing quick adjustment without tools. Four interchangeable 10-32 threaded vacuum port fittings are provided:

1. Barbed Fitting: A black zinc-plated 3/16' (5mm) barb compatible with vacuum hoses of 5/32' (4mm), 3/16' (5mm), and 7/32' (6mm).
2. 3AN Male Fitting: A black zinc-plated adapter compatible with 3AN hose ends.
3. Push-To-Connect: A nickel-plated brass fitting compatible with hard plastic 1/4' OD tubing.
4. Vacuum Plug: A black oxide stainless steel screw for maintaining constant (non-dynamic) fuel pressure, required for returnless fuel systems.

NOTE: It is recommended to use a wicking medium-strength threadlocker when installing the vacuum fitting.

FUEL COMPATIBILITY

All RA-series regulators are compatible with all gasoline types, including unleaded, leaded, oxygenated, and pre-mixes. They also support alcohol blends, including methanol, ethanol, and E85.

INCLUDED

• Main Rotating Assembly with Damper
• Mounting Bracket with M6x1mm Hardware