Most high performance Hondas require fuel delivery beyond the capacity of
the stock fuel system . This necessitates the installation of larger injectors
and a high-output aftermarket fuel pump, of the in-tank, or in-line variety.
Unfortunately, in addition to increasing available fuel volume, most of
these high-output pumps increase fuel pressure across the range as well. This
pressure increase at idle and in the lower rpm ranges can cause the engine to
run excessively rich, causing poor mileage, illegal emission levels, premature catalytic
converter failure, plug fouling, and generally poor overall performance.
To remedy the problem, it's necessary to reduce the fuel pressure by
installing an adjustable-kit such as the B&M on the stock pressure
regulator. While this will permit pressure adjustment, many enthusiasts find
that they still can't lower idle pressures enough to alleviate their problems.
The orifice (or valve) inside the Honda regulators is so small in diameter
that it serves as a restriction to fuel returning to the tank, so no amount of
adjustment will drop the pressure.
Our method for solving this problem is to drill a pressure relief hole in
the regulator, connecting the inlet area to the exit. This will allow some
excess pressure to by-pass the restrictive valve in the regulator.
We've found that drilling a hole of approximately .035" diameter will
effectively drop pressure to acceptable levels. Small drill bits like this can
be purchased through hobby shops, or most good hardware stores. Since bits of
this size are frequently smaller than the chucks can grip on most electric
drills, the use of a Dremel, or hand-twist vice is recommended.
Another picture (with the drill bit in the hole), showing that we start
the hole in the lower half of the entry orifice and angle it down toward the
The most difficult part of this modification is the removal of the
regulator from the fuel rail. In most instances, performing this operation and
installing the adjustable regulator kit should require less than an hour of your
time and the results of your efforts will be very satisfying. Your car will