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5X Racing 1990-1997 Mazda Miata Adjustable Fuel Pressure Regulator

Miata Adjustable Fuel Pressure Regulator

6295302 - 5XRAFPR
There's a lot of info regarding our regulators, all of which can be read below in the extended description.
  • OEM regulator, except with added adjustability by means of our proprietary adjustment mechanism
  • We use brand new 94-97 OEM Mazda fuel pressure regulators and convert it to an adjustable regulator by adding a proprietary adjustment mechanism. The pressure adjustment is designed to be decreased to lean the mixture for Spec Miata racing, but can be increased as well to a certain point. Forced induction vehicles might not get enough pressure from it however.
  • The 94-97 regulator fits on the 1.6L with slight fuel hose rerouting. We do not use 1.6L regulators due to poor build quality of the aftermarket regulators.
  • Not Available
    Shipping: UPS Ground or USPS Priority
    Pricing: $215.00
    5 5 6


    Why don't we rebuild used cores anymore?

    With some of the oldest used regulators being over 30-years old, we have found that the vast majority of used cores we received failed our pressure tests, determining they were unsafe to modify. There are rubber parts inside the regulator that become brittle and unstable with age. We have shifted to using brand new 94-97 OEM cores because they are more widely available and are of OEM quality. We cannot find OEM 1.6 regulators and the aftermarket versions are not OEM build quality, so we have made the decision to encourage using the 94-97 1.8 regulators on the 1.6. The only difference is the fuel hose design. The 90-93 has a curved hose, and the 94-97 has a straight hose. The straight hose will work on the 1.6 with slight rerouting of the fuel line, well within the working limits of the hoses. 

    What's the scoop?
    What we are offering here is an OEM Mazda fuel pressure regulator modified to be made adjustable by adding our custom fabricated mechanism. OEM fit and finish, but totally transformed into a trick adjustable factory quality regulator.

    Why is this better than the other adjustable fuel pressure regulator kits out there?
    Our kit is better because it utilizes the factory fuel pressure regulator, which is a practically flawless part to begin with. Very rarely have we had a problem with one in the hundreds we've produced. Also, our kit does not have anything to do with modifying or altering the path of your fuel lines. We don't require cutting into your fuel lines, which causes potential for leaks and fire. It uses the factory vacuum line, which keeps the pressure consistent, something that you will not easily get with a universal adjustable fuel pressure regulator. Universal fuel pressure regulators dip and spike with different engine loads and rpm spikes (missed shifts), ours stays consistent just as your factory regulator would. We didn't take the easy way out with this and use a universal adjustable fuel pressure regulator, we put a lot of thought and development into this part and have been track testing it since late 2010 down here in Florida with no failures and successful results.

    What will it do for my Miata?
    Our fuel pressure regulator will allow you to adjust your fuel pressure at your fuel rail by simply turning an adjustment screw, which in turn alters your air/fuel ratio by increasing or decreasing the fuel pressure to your engine. Adjusting your fuel pressure lower or higher will lean or richen your air/fuel ratio, which is essential for tuning your Miata's engine for maximum horsepower, especially in stock based classes like Spec Miata where modifications are extremely limited. For example: dialing in more fuel equals a richer mixture of air and fuel, which will benefit low rpm torque and horsepower for tracks that are tight and have low speed corners. Dialing in less fuel will lean your mixture of air and fuel, which will benefit high rpm horsepower for tracks that are 3rd gear through 5th gear tracks and do not have tight turns. So, in essence, our product will allow you to adjust your fuel pressure freely, which in turn adjusts your air/fuel ratio for different tracks based on your need of more horsepower or more torque.

    What will I need to use this regulator on my car?
    Using our regulator is as easy as removing the factory regulator on your car, sending it to us, then reinstalling it back on your car. It is the factory regulator, so there is no worry about the fit and finish. When you install your new regulator, simply follow your cars repair manual for "fuel pressure regulator removal/installation". We suggest setting your fuel pressure to the factory setting range of 32-38 psi at idle, then tune from there. To properly tune, You MUST have a fuel pressure gauge either installed full time inline with your fuel line, or an external attachable gauge to dial in your specified fuel pressure while idling in the shop. Of course we would suggest adding on our 5X Racing Inline Fuel Gauge Kit by choosing it from the drop down list above. And, we HIGHLY suggest picking up an air/fuel ratio gauge, such as the AEM or Innovate Motorsports versions we sell here at 5X Racing to be able to accurately monitor and dial in your fuel ratio. If you don't have a fuel pressure gauge, or air/fuel ratio gauge, our regulator is practically useless to your tuning needs.



    • 6295302 - 5XRAFPR
    • 6295302
    • 5XRAFPR
    • 5X Racing
    • New

    Shipping Information

    • Item Requires Shipping
    • 1.0 lbs.
    • W6.0000” x H2.0000” x L9.0000”
    • Free U.S. Over $150
    • UPS Ground or USPS Priority

    Customer Reviews

    Comment Total Reviews (4)

    Nice Job 5X
    • Currently 5/5 Stars

    Reviewed by:

    Product ownership: Less than 3 months

    Purchased from: 5X Racing

    5X Racing did a beautiful job putting this product together. Thanks

    great improvement
    • Currently 5/5 Stars

    Reviewed by:

    Product ownership: Less than 1 year

    Purchased from: 5X Racing

    I added the afpr and a set of headers 4to1 I gained 11 hp. Went from 108 to 119. We adjusted on the dyno we had been running very rich and had tried everything to lean it out. Great product.

    Great Tuning Aid
    • Currently 5/5 Stars

    Reviewed by:

    Product ownership: Less than 1 year

    Purchased from: 5X Racing

    This product was easy to install with the directions provided. The quality of the product is obvious. I used this to help tune my 1.8L engine last summer on a dyno, and gained about 5HP over the stock setting.

    Great Adj Fuel Reg, Easy, simple, oem look
    • Currently 5/5 Stars

    Reviewed by:

    Product ownership: Less than 1 week

    Purchased from: 5X Racing

    Incredibly easy install/swap as compared to a universal regulator. Saved money and time going this way. Reg was easy to adjust to lean out the a/f mix. My car is also street registered and this part is not going to attract attention. Did what is designed to do. Satisfied.

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