AEM 25-304BK Adjustable Fuel Pressure Regualtor User Manual

Adjustable

Fuel Pressure

,!

Regulator

Installation Instructions for:

Part Numbers

25-300
25-301
25-303
25-304

U.S. Patent # 6,298,828

WARNING:

Due to the fact that this installation deals with your fuel system
this installation is not for the mechanically challenged! If you are
not mechanically inclined or do not understand the procedure
please do not attempt the installation. Refer the installation to a

reputable mechanic.

ADVANCED ENGINE MANAGEMENT INC.

2205 126

Phone: [phone] Fax: [phone]

© 2000 Advanced Engine Management, Inc.

TH

Street, Unit A Hawthorne, CA. 90250

Http://www.aempower.com

Part Number: 10-290

This part is legal in California for racing vehicles ONLY and should NEVER be used on public highways.

Congratulations! You have just purchased the finest adjustable fuel pressure regulator for

your car at any price!

AEM billet aluminum adjustable pressure regulator.

The AEM adjustable regulator bolts directly to the stock Honda or the AEM high volume fuel rail.
It is CNC machined from 6061 T-6 aluminum. The fuel outlet port is tapped to 9/16-18 threads,
which allows the use of several different hoses ranging from the stock Honda fuel return hose to
–8 AN hose. The vacuum reference is 1:1 ratio so for every pound of boost on a turbocharged
or supercharged application yields a 1-pound rise in fuel pressure. The range of adjustability is
from 20 PSI to the maximum the fuel pump can deliver.

A unique feature of the AEM adjustable pressure regulator is that the discharge port in the
regulator is changeable. This allows the user to tailor the regulator return volume to match their
fuel pump. A common problem that occurs when using a fixed orifice in a “universal” regulator is
that the fuel pressure cannot be effectively controlled when the fuel pump volume is significantly
higher than stock. In the case of too small of a discharge orifice, there is a large pressure spike
associated with rapid deceleration because the orifice cannot flow enough fuel when the
diaphragm is fully deflected to the open position. This causes a momentary rich condition, which
may lead to a rough idle quality until the pressure stabilizes. Conversely if the discharge orifice
is too large the adjustment is difficult because the response of the fuel flow out of the orifice is
too rapid which makes the adjustment screw too sensitive. The AEM regulator is packaged with
three orifice sizes, .100”, .150” and .200”. They are easily changed by removing the diaphragm,
unscrewing the orifice, and replacing it with the desired size orifice. The size range provided
with the kit is enough to cover any pump from a stock Honda pump to the largest after-market
pump available. The replaceable orifices are color coded for easy identification.

Inline
Base

Offset

Base

Note: Honda uses two styles of fuel pressure regulator bases. Before proceeding with
your installation please compare the fuel pressure regulator on your vehicle and your
new AEM adjustable fuel pressure regulator with the above diagrams.

Bill of Materials for 25-300:

2 2-609 -6 to 7mm Barb Fuel Return Fitting
1 2-611 Vacuum Fitting
1 2-612 Spring Cap
1 2-698 .250ORIFICE,BALLPRESSREG
1 2-697 .175ORIFICE,BALLPRESSREG
1 2-696 .1OrificeBALLPRESSREG
1 2-8000 Fuel Pressure Regulator Top
1 2-8100 Fuel Pressure Regulator Bottom (Inline)
1 1-3007 Crush Washer
1 1-3010 O-Ring
6 1-2023 Socket Bolt, SS 8-32 x 5/16”
1 1-2021 Socket Screw, SS 10-32 x 1”
1 1-2022 Nut, Jam SS 10-32
1 2-301 Diaphragm
1 1-122 Spring
2 1-2045 Socket Bolt, SS M6 x1 x 12mm
2 1-3016 Washer, SS M6

Bill of Materials for 25-301:

1 2-609 -6 to 7mm Barb Fuel Return Fitting
1 2-611 Vacuum Fitting
1 2-612 Spring Cap
1 2-613 0.20” Orifice
1 2-614 0.15” Orifice
1 2-615 0.10” Orifice
1 2-8000 Fuel Pressure Regulator Top
1 2-8101 Fuel Pressure Regulator Bottom (Offset)
1 1-3007 Crush Washer
1 1-3010 O-Ring
6 1-2023 Socket Bolt, SS 8-32 x 5/16”
1 1-2021 Socket Screw, SS 10-32 x 1”
1 1-2022 Nut, Jam SS 10-32
1 2-300 Diaphragm
1 1-122 Spring
2 1-2045 Socket Bolt, SS M6 x1 x 12mm
2 1-3016 Washer, SS M6