AEM HondaAcura Adjustable Fuel Pressure Regualtor 25392 User Manual

							ADVANCED ENGINE MANAGEMENT INC. 
2205 126TH Street, Unit A Hawthorne, CA. 90250 
Phone: (310) 484-2322 Fax: (310) 484-0152 
Http://www.aempower.com 
Part Number: 10-7054 
 2004 Advanced Engine Management, Inc. 
 
 
 
 
 
 
 
 
Adjustable 
Fuel Pressure 
Regulator 
Rebuild Kit 
 
Installation Instructions for: 
Part Number 
25-392 
 
 
 
 
 
 
 
 
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. 
  
						

							This part is legal in California for racing vehicles ONLY and should NEVER be used on public highways. 
 
 
 
Congratulations!  You have purchased the finest adjustable fuel pressure regulator for your car 
at any price! 
 
AEM billet aluminum adjustable pressure regulator. 
The AEM adjustable regulator 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  up  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  up  to  the  largest  after-market  pump  available.  The 
replaceable orifices are color coded for easy identification.  
 
Bill of Materials for 25-392: 
 
 
Note: There are two different styles of AEM adjustable fuel pressure 
regulator diaphragm/orifice sets- a flat seat and a ball seat. Parts from the 
two different styles are not interchangeable. When replacing an old 
diaphragm with a new one from this rebuild kit, the fuel return orifice MUST 
be changed to the ball seat style (included in this rebuild kit) if your 
regulator is not already so equipped. 
 
 
 
 QtyPart NumberDescription
12-301Diaphragm, Fuel Pressure Regulator
12-696.1 Orifice, Ball Press Reg
12-697.175 Orifice, Ball Press Reg
12-698.250 Orifice, Ball Press Reg
11-3010O Ring,Fuel Pressure Regulator
110-7054Instructions, 25-392  
						

							WARNING!!! 
Read and understand these instructions BEFORE attempting to install this product 
 
 
 Do not smoke while working on the fuel system. 
 Keep open flames or sparks away from your work area. 
 Be sure to relieve fuel pressure while engine is off. 
 
1) Getting started 
a) Make sure vehicle is parked on a level surface. 
b) Set parking brake. 
c) Disconnect the negative cable from the negative battery terminal. 
d) If engine has run within the past two hours let it cool down. 
e) Clean the area on the fuel rail adjacent to the regulator. 
f) Relieve fuel pressure. Refer to factory service manual for proper procedure. 
 
2) Fuel pressure regulator removal 
a) Place a rag or shop towel under the fuel pressure regulator return line.  
b) Disconnect the fuel return line at the bottom of the fuel pressure regulator. 
c) Disconnect the vacuum hose from the fuel pressure regulator. 
d) Place a rag or shop towel over the fuel pressure regulator. 
i) Remove the two 6mm retaining bolts if regulator is mounted to a factory fuel rail. 
(1) If using an AEM universal fuel pressure regulator, remove fuel inlet hose. 
ii) Remove the fuel pressure regulator from the vehicle. 
 
3) Changing the diaphragm/orifice 
a) Remove the six bolts from the top of the fuel pressure regulator. 
i) When removing the six bolts from the top of the fuel pressure regulator a 9/64” allen key should be 
used. 
(1) Torque to 24 lbf-in. 
(2) There is a constant pressure applied to the diaphragm by the spring inside the fuel regulator. Make 
sure parts do not get lost upon removal of these bolts. 
ii) When removing the orifice a 3/8” socket should to be used. 
(1) Note:  Be careful not to scratch or damage the surface of the orifice in any way, as it is a 
precision ground surface for the diaphragm to seal on. 
(2) Torque to 10 lbf-ft. 
(3) There are three different size orifices supplied in the AEM fuel pressure regulator kit, which are 
indicated by three different colors.  Black = .100”  Silver =.150”  Gold = .200” 
(4) Upon re-installation of the orifice use a light coat of oil on the threads to prevent galling. 
iii) Re-assemble the fuel pressure regulator.  Assembly diagram at the end of the instructions. Make sure 
the diaphragm is properly seated in its groove. Use care to avoid pinching the diaphragm between the 
top and bottom regulator housing. 
 
4) Finishing touches 
a) Reinstall the regulator by reversing the removal procedures from step 2.  
b) Connect the negative battery terminal. 
c) Turn the ignition switch to the on position for approximately two seconds.  Do not operate the starter.  
Then turn the ignition switch to the off position. 
d) Repeat this procedure three times, and then check all components that were removed during installation for 
any signs of fuel leakage. 
e) If there are signs of leakage you MUST correct the leak before proceeding. 
f) If there are no signs of leakage, then start engine and again check for leaks. If there is any sign of leaking 
you MUST repair the leak before driving the vehicle. 
g) Note:  To check the fuel pressure, start the engine.  Measure the fuel pressure with the engine idling 
and vacuum hose of the fuel pressure regulator disconnected from the fuel pressure regulator and 
pinched.  
  
						

							 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
For Technical Inquiries 
Please E-Mail us at 
[email protected] 
Jam Nut Set Screw 
Allen Bolts (6) 
Vacuum Fitting 
Spring Cup 
 (Not Shown) 
Regulator 
 Spring 
Diaphragm 
Fuel Return 
Fitting 
Lower Housing 
Upper Housing 
Orifice 
3 Provided