AEM High Volume Fuel Rail 25108BK User Manual

							ADVANCED ENGINE MANAGEMENT INC. 
2205 126TH Street, Unit A Hawthorne, CA. 90250 
Phone: (310) 484-2322 Fax: (310) 484-0152 
www.aempower.com 
Instructions Part Number: 10-315
 
88-95 Honda Multi-Port Fuel Injected D-Series Hi-Flow Fuel Rail  
© Copyright 2001 
Some applications are legal in California for racing vehicles which may never be used on public highways 
 
 
HI-FLOW 
FUEL RAIL 
 
 
 
 
 
 
Installation Instructions for: 
Part Number 25-108 
88-91 Civic/CRX SI 
92-95 Civic 
 
  
						

							 
Congratulations!  You have just purchased the finest Hi-Flow Fuel Rail for your car at 
any price! The AEM Hi-Flow Fuel Rail is the result of extensive development on a wide 
variety of cars. It is the most advanced Hi-Flow Fuel Rail on the market and is 
specifically engineered for its application. All AEM Hi-Flow Fuel Rails are CNC 
machined from 6061 T-6 billet aluminum and feature a ½-inch bore capable of flowing 
enough fuel to support most high-performance engines. This larger bore also dampens 
the back pulse created by oversized injectors on high-output applications. The AEM 
Fuel Rail also works perfectly with stock injectors. Each Fuel Rail includes an additional 
port for the installation of a nitrous system or an external fuel pressure gauge. The ends 
of the rail are tapped to accept either –6 or –8 line and a custom fitting that allows for 
the use of the stock fuel hose. AEM’s Hi-Flow Fuel Rail Kit includes everything needed 
for a professional bolt-in installation. 
 
 
 
 
Bill of Materials for: 25-108 
 
 
 
QTY. Part Number  Description 
1  2-5008  D-Series Fuel Rail 
2  2-125  D-Series Fuel Rail Spacer  
1  2-602  Honda Fuel Fitting w/o Hole  
1  2-603  Honda Fuel Fitting w/ Hole 
1  2-604  -6 Fuel Rail Plug 
2  1-121  1/8” Pipe Plug 
2  1-3007  -6 Crush Washer 
4  1-3008  Fuel Injector O-Ring 
2 10-922S AEM Silver Decal 
1 10-315  Instructions  
						

							 
Read and understand these instructions BEFORE attempting to install 
this product. 
 
Note:  This fuel rail kit requires the removal and reinstallation of fuel system related components.  
If you are not familiar with the installation and/or the operation of these components then please 
refer this installation to a qualified professional. 
 
 
 
• Do not smoke while working on the fuel system. 
• Keep open flames and/or sparks away from your work area. 
• Be sure to relieve the fuel pressure while the engine is off. 
 
1) Getting started
 
a)  Make sure vehicle is parked on a level surface. 
b)  Set parking brake. 
c)  Disconnect negative battery terminal. 
d)  If engine has run within the past two hours let it cool down. 
e)  Clean the area around the fuel rail so that dirt cannot get into the engine. 
 
2)  Relieving fuel pressure 
a)  Remove the fuel filler cap. 
b) On models equipped with a 6mm service bolt: (Fig. 1)  
i)  Use a box end wrench on the 6mm service bolt on top of the fuel filter or fuel rail, while 
holding the special banjo bolt with another wrench. 
ii)  Place a rag or shop towel over the 6mm service bolt. 
iii)  Slowly loosen the 6mm service bolt one complete turn. 
iv)  Leave service bolt loose until all pressure has been relieved. 
v)  Retighten service bolt to 10lb-ft. 
 
 
Fig. 1 
WARNING! 
 
Service Bolt 
Fuel Filter Shop Towel  
						

							  c) On models not equipped with a 6mm service bolt: 
i)  Use a box end wrench on the 12mm banjo bolt on top of the fuel filter. 
ii)  Place a rag or shop towel over the 12mm banjo bolt. 
iii)  Slowly loosen the 12mm banjo bolt one complete turn or until all pressure has been relieved. 
iv)  Torque the 12 mm banjo bolt to 25lb-ft. 
 
3)  Removal of stock fuel rail, injectors and fuel pressure regulator 
a)  Loosen and remove the nut holding the fuel inlet banjo fitting to the fuel rail. Be careful not to 
loose either of the two crush washers.  
b)  Disconnect the wire harness connectors from the fuel injectors. 
c)  Disconnect the vacuum hose from the fuel pressure regulator. 
d)  Place a rag or shop towel over the fuel pressure regulator and remove the two 6mm retaining 
bolts. 
e)  Position the fuel pressure regulator out of the way. Be careful not to loose the o-ring that goes 
between the fuel rail and the fuel pressure regulator.  
f)  Loosen and remove the retainer nuts/bolts on the fuel rail, injector harness, and any other 
components that may be bolted to the fuel rail. 
g)  Remove the fuel rail from the intake manifold.    
h)  Remove the fuel injectors from the intake manifold. Note: Some models have an injector insulator 
on the injector tip (the end of the injector that goes into the intake manifold) and some models do 
not.  Note the arrangement your model has and be sure to reassemble the injector assembly 
correctly. 
i) Refer to figure 2 for proper disassembly/reassembly. 
 
 
 
 
 
 
Fig. 2 
Cushion Ring 
(Inspect) O-Ring 
(Replace) Torque to 9lb-ft. 
Injector Insulator 
(Some Models: Inspect) Seal Ring 
(Inspect) 
Regulator 
Wire Harness  
						

							  j)  Inspect all seals, o-rings, and washers.  If any of these components look at all worn or damaged, 
then replace with genuine Honda parts. 
 
4)  Assembly of the AEM Fuel Rail 
a)  Your fuel rail kit comes with two different types of banjo adaptors. One has a through hole on the 
side and one does not. Look at your factory fuel rail to determine which fitting is the correct one 
for your vehicle. 
b)  Lubricate the threads of the correct banjo adaptor fitting with a light coat of engine oil.  Place a –6 
crush washer over the side with the larger threads and install the banjo adaptor fitting into the end 
of the AEM Fuel Rail that matches the placement of the fitting on the stock fuel rail. Be sure that 
the crush washer is centered under the head of the fuel inlet fitting. (Fig. 3)   
c)  Install the –6 plug on the opposite end of the rail. Once again lubricate the threads and place a –6 
crush washer over the threaded side of the plug. Be sure that the crush washer is centered under 
the head of the fuel inlet fitting. (Fig. 4)   
 
Fig. 3  Fig. 4 
 
d)  The AEM Fuel Rail comes with an additional fuel port. If you are running a wet nitrous oxide 
system, or a fuel pressure gauge, then this port may be used for the additional fuel supply.  If you 
are not in the need of an additional fuel source install the supplied 1/8” NPT plug. (Fig. 5)   
Note: When installing the tapered plug or any other tapered fitting into the AEM Fuel Rail, use 
only a lubricant or anti-seize on the threads.  Do not under any circumstances use liquid 
Teflon or Teflon tape as a sealant for any tapered plug or tapered fitting in any fuel system. 
e)  Your kit comes supplied with two 1/8 NPT plugs. DO NOT
 install the additional 1/8” NPT plug 
if you are going to be using the stock regulator or an AEM Adjustable Regulator. (Fig. 6) 
 
Fig. 5  Fig 6  
						

							  f)  Remove the old o-rings that are on top of the injectors. Coat the new o-rings, supplied with the kit, 
with clean engine oil and install them onto the injectors. 
g)  Insert the o-ring end of the injectors into the AEM Fuel Rail.  
h)  Coat the seal rings with clean engine oil and then install them into the intake manifold. 
i)  Install the fuel rail/injector assembly back onto the vehicle. Make sure that all of the seals and o-
rings are properly seated, and installed without damage.  
j)  Your AEM Fuel Rail was designed to accommodate two different generations of the Civic. 
i)  If you are installing the fuel rail on an 88-91 Civic/CRX you will need to install 2 mounting          
spacers into the machined pockets on the mounting flange of the rail. (Fig. 7) 
ii)  If you are installing the fuel rail on a 92-95 Civic there is nothing additional needed for proper 
installation to the intake manifold. 
k)  Install and tighten the fuel rail retainer nuts to 9lb-ft. 
 
Fig. 7 
 
l)  Install the fuel pressure regulator onto the AEM Fuel Rail.  Make sure that the o-ring is properly 
installed between the regulator and the fuel rail. 
m)  Connect the vacuum hose to the top of the fuel pressure regulator. Some installations require the 
replacement of this hose with one that is longer.  
n)  Remove the injector harness from the plastic case. Re-route the harness behind the rail and re- 
connect the harness to the injectors.  
o)  Install the fuel supply line to the AEM Fuel Rail. 
i)  Be sure that a crush washer is positioned on both sides of the banjo fitting. 
ii)  Torque the retaining nut to 12lb-ft.  
DO NOT OVER TIGHTEN.  
iii) Make sure the plug on the end of the fuel rail is tight. 
p)  Install any remaining components that were removed during disassembly.  
						

							 
5)  Final Assembly and Inspection 
a)  Connect the negative battery terminal. 
b)  Turn the ignition switch to the on position for approximately two seconds and then turn the ignition 
switch to the off position.  Do not operate the starter.  
 
i)  Repeat this procedure three times, and then check all components that were removed during 
installation for any signs of fuel leakage. 
ii) Check the area around the fuel inlet fitting, the –6 plug and the 1/8” NPT plug.  If these 
three items were not installed correctly then they may be prone to leak. 
iii)  If there are signs of leakage you MUST
 correct the leak before proceeding. 
c)  If there are no signs of leakage, then start engine and again check for leaks. 
d)  If there are no signs of leakage on your final inspection, then the installation is complete. 
 
 
 
 
 
 
 
 
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