Fuel Pressure Regulator, EFI -8 / -6 AN E85, Black/Green
Quick Overview
- Adjustable EFI fuel pressure regulator, 35-78 psi
- 2 x -8 AN ORB in/out, -6 AN ORB return
- 1:1 boost/vacuum referenced, bypass style
- Stainless serviceable seat; E85, gas and diesel safe
- Anodized aluminum, Black/Green; bracket included
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$149.99
per EACH (USD)EFI Fuel Pressure Regulator, -8 / -6 AN ORB, E85, Black/Green
Adjustable 35-78 psi, 1:1 boost/vacuum referenced, two -8 AN ORB side ports and a -6 AN ORB bottom return.
The Racetronix REG-FI886BGN is a bypass (return-style) fuel pressure regulator for fuel-injected engines. Fuel from the pump enters through either side port, the regulator holds the pressure you set, and all surplus fuel leaves through the bottom port back to the tank. Fuel pressure rises and falls 1:1 with boost and vacuum when the reference port is connected to the intake manifold.
Key features
- Two -8 AN ORB side ports (3/4"-16), fuel in and out. Either side can be the inlet; plug the other for a single-line setup.
- One -6 AN ORB bottom port (9/16"-18): the return to the tank.
- 35-78 psi adjustment range (maximum).
- 1:1 boost/vacuum reference through a 1/8" female NPT port, 5/32" barb included.
- 1/8" female NPT gauge port with a colour-matched plug.
- Ball-seat valve, resistant to clogging, for stable pressure control.
- Stainless steel valve seat where the ball closes, serviceable.
- E85, gasoline and diesel compatible composite fibre-reinforced diaphragm.
- O-ring sealed adjustment screw (5 mm Allen, 17 mm lock nut) to stop boost/vacuum bleed.
- Mounting bracket and stainless hardware included. Field serviceable, fully assembled and tested.
- Colour shown as it looks in daylight; see About anodized colours under Colours and sizes before ordering.
Port guide: which port is which
Ports and controls. Shown in black/silver; the layout is the same in every colour. Click to enlarge.
The bottom port is the return. Click to enlarge.
| Side ports (2) | -8 AN ORB, 3/4"-16. Fuel in and fuel out. Both open into the same pressure chamber, so either one can be the inlet. |
| Bottom port (1) | -6 AN ORB, 9/16"-18. Return only: run it back to the tank with no restriction. Never connect the pump feed here. |
| Gauge port | 1/8" female NPT, plug fitted. Pipe thread: seal it with a fuel-resistant thread sealant. |
| Reference port | 1/8" female NPT in the cap, 5/32" barb fitted. Hose to the intake manifold below the throttle body. |
| Adjuster | 5 mm Allen screw with a 17 mm lock nut on top of the cap. |
The fuel ports are O-ring boss (ORB) straight threads. The O-ring on the fitting does the sealing: use ORB fittings with their O-rings, wet the O-ring with clean fuel or oil, and do not use tape or sealant. Pipe-thread (NPT) fittings will not seal in these ports.
How to plumb it
Three common layouts. Red is the pressure feed, blue is the return. Click to enlarge.
- A. Two rails (most V8s): feed both rails from the pump (Y-block or crossover), then run each rail outlet into one regulator side port. The return leaves from the bottom.
- B. One rail with an inlet and an outlet: pump to the rail, rail outlet into one side port. Plug the other side port with a FIT-481308.
- C. Rail with a single inlet (including many factory "returnless" rails): pump into one side port, the other side port out to the rail. The regulator sits before the rail.
In every layout the bottom port is the return. Run it back to the tank, ideally into the top of the tank or the pump module's return fitting, so returning fuel does not aerate the pump pickup. A -6 AN return suits most builds. Mount the regulator away from exhaust heat, upright or on its side, using the supplied bracket.
Setting the fuel pressure
- Fit a gauge to the 1/8" NPT gauge port (or the rail test port).
- Turn the key on without starting, two or three times, to prime the system. Check every joint for leaks before you start the engine.
- Start the engine and let it idle. Pull the reference hose off the regulator barb and plug the hose (not the regulator) so the engine does not run lean on a vacuum leak. The gauge now shows base pressure.
- Loosen the 17 mm lock nut. Turn the 5 mm Allen screw clockwise to raise pressure, counter-clockwise to lower it. Go a quarter turn at a time and let the gauge settle.
- Hold the screw still and tighten the lock nut. Refit the reference hose.
With the hose reconnected, idle pressure reads lower than base by the amount of manifold vacuum (typically 8 to 10 psi), and under boost it rises 1 psi for every 1 psi of boost. Example: 43.5 psi base with 15 psi of boost gives 58.5 psi at full boost. Your pump must still supply the engine's flow at that pressure.
Use the pressure your injectors and tune are calibrated for. Many port-injected engines run 43.5 psi (3 bar); many late factory returnless systems run about 58 psi. Stay within the 35-78 psi range.
Not using the reference port (naturally aspirated, constant pressure)? Leave the barb open to the air. Do not cap it.
Fittings for this regulator
Regulators ship without port fittings so you can match your lines. Racetronix fittings for this regulator:
Side ports (-8 AN ORB)
| Part | Description |
|---|---|
| FIT-481308 | Plug, -8 AN ORB |
| ADF-495101 | -8 AN ORB to -6 AN JIC male |
| ADF-495103 | -8 AN ORB to -8 AN JIC male |
| FIT-680708 | -8 PTFE hose end to -8 AN ORB, straight |
| FIT-689708 | -8 PTFE hose end to -8 AN ORB swivel, 90° |
| ADF-8RM8RM | Swivel coupler, -8 AN ORB male both ends |
Bottom return port (-6 AN ORB)
| Part | Description |
|---|---|
| ADF-495100 | -6 AN ORB to -6 AN JIC male |
| ADF-495102 | -6 AN ORB to -8 AN JIC male |
| FIT-680706 | -6 PTFE hose end to -6 AN ORB, straight |
| FIT-689706 | -6 PTFE hose end to -6 AN ORB swivel, 90° |
Gauge, reference and service
| Part | Description |
|---|---|
| FPG-RTB00100 | Pressure gauge, 0-100 psi, 1.5", liquid filled |
| ADF-481603 | -3 AN JIC male to 1/8" NPT male, for a remote gauge line |
| ADF-481604 | -4 AN JIC male to 1/8" NPT male, for a remote gauge line |
| ADF-B18N532SS | Replacement reference barb, 1/8" NPT male to 5/32" |
| REG-FIVD2 | Valve and diaphragm service part |
Specifications
| Part number | REG-FI886BGN |
| Colour | Black/Green |
| Type | Bypass (return-style) EFI regulator, boost/vacuum referenced 1:1 |
| Adjustment range | 35-78 psi (maximum) |
| Side ports | 2 x -8 AN ORB (3/4"-16), in / out |
| Return port | 1 x -6 AN ORB (9/16"-18), bottom |
| Gauge port | 1/8" female NPT, colour-matched plug |
| Reference port | 1/8" female NPT, 5/32" barb included |
| Adjuster | 5 mm Allen screw, 17 mm lock nut, O-ring sealed |
| Valve | Ball and seat; stainless steel seat, serviceable |
| Diaphragm | Composite fibre-reinforced; E85, gasoline and diesel compatible |
| Finish | Anodized aluminum |
| Included | Regulator, mounting bracket, stainless hardware, 5/32" barb |
| Service | Field serviceable; fully assembled and tested |
Colours and sizes
| Colour | Part |
|---|---|
| Black/Silver | REG-FI886BS |
| Matte Black | REG-FI886BB |
| Black/Blue | REG-FI886BBL |
| Black/Gold | REG-FI886BG |
| Black/Green | REG-FI886BGN |
| Black/Purple | REG-FI886BP |
| Black/Red | REG-FI886BR |
| Black/Rainbow | REG-FI886BRW |
| Titanium/Silver | REG-FI886TI |
Our photos are taken to show each colour as it looks in normal daylight. Anodizing is a dyed finish on aluminum, not paint: our gold is a yellow-gold, not metallic gold, and every colour can look different under shop lights, at night, or next to other parts under the hood. We cannot match anodized colours to your paint, powder coat or other components, and we do not accept returns because a colour does not match your vehicle. If you need an exact match, choose black or black/silver.
Other port sizes: REG-FI10106 (-10 / -6 AN), REG-FI666 (-6 / -6 AN).
Frequently asked questions
Which port is the inlet and which is the outlet?
Either side port can be the inlet. Both side ports open into the same chamber, so the second side port is a pass-through to a rail or gets plugged. The bottom port is always the return to the tank.
Can I use just one side port?
Yes. Plug the unused side port with a FIT-481308 (or another -8 AN ORB plug with an O-ring).
Which way do I turn it to raise the pressure?
Clockwise raises pressure, counter-clockwise lowers it. Loosen the 17 mm lock nut first and retighten it when you are done.
Do I have to connect the vacuum/boost port?
On a boosted engine, yes: connect it to the intake manifold so fuel pressure follows boost. On a naturally aspirated engine it is optional. If you do not use it, leave the barb open to the air; do not cap it.
Pressure stays high even with the screw backed right out. Why?
The return is restricted or plumbed wrong. Check that the pump feed goes to a side port, not the bottom, and that the return line is large enough and runs back to the tank without kinks, small fittings or a restrictive entry. Debris under the valve seat can do the same; the regulator comes apart for cleaning.
Pressure falls to zero after I shut the engine off. Is something wrong?
No. Adjustable diaphragm regulators like this one let pressure bleed down after key-off. That is normal. A longer prime before cranking helps.
Will the colour match my car or engine bay?
Not exactly. The photos show each colour in normal daylight, but anodized colours look different under other lighting and next to reflective parts, and we cannot match them to paint or other components. Colour mismatch is not a reason for return. If you need an exact match, choose black or black/silver.
Will it work with E85?
Yes. The diaphragm and seals are E85, gasoline and diesel compatible.
Can I convert a returnless system?
Yes, with layout C: pump into one side port, the other side port to the rail, and a new return line from the bottom port back to the tank.
Which size should I buy?
Match the side ports to your feed line: -10 for large -10 feed systems, -8 for most -8 builds, -6 for -6 lines. All three use the same -6 return.
Questions and support
Not sure which regulator or fittings your build needs? Email [email protected] before you order.
Racetronix provides technical support to verified customers through our support forum, not by phone or email. Please request forum access when you place your order so your account is approved before your parts arrive. The forum is moderated, open 24/7, and holds a knowledge base going back to 1999.
