How Do You Spell Relief?

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.

This is a picture of a Honda fuel pressure regulator with the "top" sawed off for installation of a B&M adjustability kit.

The fuel entry is the orifice surrounded by the "O" ring and the exit is the tube protruding from the bottom of 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.

In this picture, you can see we've removed the "O" ring and drilled the pressure relief hole inside the fuel entry orifice.

Note that the hole we drill is angled toward the exit end of the regulator.

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 exit.

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 thank you.