AEM 25-392 Honda/Acura Adjustable Fuel Pressure Regualtor - Manual (Page 2)

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:
Qty Part Number Description
1 2-301 Diaphragm, Fuel Pressure Regulator
1 2-696 .1 Orifice, Ball Press Reg
1 2-697 .175 Orifice, Ball Press Reg
1 2-698 .250 Orifice, Ball Press Reg
1 1-3010 O Ring,Fuel Pressure Regulator
1 10-7054 Instructions, 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.