If you're running a built or boosted Nissan engine on the KA, SR, or RB platforms, fuel pressure management is one of the parts of the build you can't afford to get wrong. Too low and the engine runs lean under load. Too high and you're flooding the cylinders and risking damage. The ISR Performance Fuel Pressure Regulator Kit V2 is a complete bolt-on solution for any of these platforms, with full E85 compatibility and every component you need to install it in a single package.
What It Is
The ISR Performance Fuel Pressure Regulator Kit V2 is a complete universal-fitment fuel pressure regulator kit assembled in house and designed for Nissan KA24DE, KA24DET, SR20DE, SR20DET, and RB-series engines. The kit is built around ISR's Version 2 bypass-style fuel pressure regulator with full E85 compatibility, and it ships with the gauge, fuel rail adapter, fittings, mounting bracket, and fuel hose needed to complete the install. The "V2" designation refers to ISR's updated regulator design with E85-compatible internals and seals.
What It Does
Proper fuel pressure is essential to the operation of any fuel-injected engine. The fuel pressure regulator manages the pressure of fuel delivered to the injectors, which directly affects how much fuel is sprayed into the cylinders during each injector pulse. When fuel pressure is off, the engine can't deliver the air-fuel ratio it's targeting, regardless of how good the tune is.
Symptoms of improper fuel pressure include rough running, irregular idle, hesitation under acceleration, and loss of power. On modified engines (turbocharged, high horsepower, larger injectors, or E85 fuel), the factory fuel pressure regulator often can't hold the pressures needed to support the build. Replacing the factory unit with an aftermarket adjustable regulator solves that and gives you the ability to dial in fuel pressure to match your specific setup.
Why Bypass Style
The ISR V2 regulator uses a bypass design, which is the architecture used on most performance fuel pressure regulators for modified engines. A bypass regulator works by allowing excess fuel to return to the tank, which keeps fuel pressure stable as injector demand changes. This is significantly more accurate than the factory dead-head style regulators used on some platforms, and it's the right choice for any build running larger injectors, forced induction, or alternative fuels like E85.
E85 Compatibility
The V2 designation specifically refers to the E85-compatible internals and seals used in this regulator. E85 (and other high-ethanol fuels) is corrosive to many of the materials used in older fuel system components, including rubber seals, certain metals, and some plastic parts. A regulator that wasn't designed for E85 will degrade over time, eventually leaking, sticking, or failing entirely.
The ISR V2 is built with materials rated for continuous E85 exposure, and the included fuel hose is also E85 compatible. The entire kit can be installed on a flex fuel or E85-dedicated build without worrying about material compatibility issues down the road. If you're not running E85, the kit still works perfectly on pump gas. The E85 compatibility is forward-looking insurance even if you're not running ethanol blends today.
Complete Kit Saves Time and Money
Piecing together a fuel pressure regulator setup from individual components is a common path, and it's also a common source of fitment problems. The regulator from one brand uses different fitting sizes than the gauge from another brand, the fuel rail adapter doesn't match the rail, the hose is the wrong material for the fuel you're running. By the time you've sorted all of that out, you've spent more than you would have on a complete kit and you've burned a weekend chasing adapters.
The ISR kit ships with every component pre-matched for compatibility: regulator, gauge, fuel rail adapter, fittings, bracket, and hose. Everything is sized to work together, and the materials are consistent throughout (E85 compatible across the whole kit). For builders who'd rather spend their time tuning the car than sourcing parts, this is the easier path.
Fitment and Compatibility
This regulator kit is designed for the following Nissan engine platforms:
- KA24DE and KA24DET — the factory 240SX engine in naturally aspirated and turbocharged configurations
- SR20DE and SR20DET — the popular swap engine for 240SX and other S-chassis builds
- RB-series engines — RB20, RB25, RB26 in their various configurations
The kit is universal in the sense that the regulator, gauge, fittings, and hose work with any of these engines. The fuel rail adapter is designed to connect to factory or aftermarket fuel rails on these platforms. Fuel system layout varies between engines and builds, so verify that your specific setup can accommodate the regulator placement and hose routing before installation.
Fuel compatibility: The kit is rated for gasoline (pump or race fuel) and E85. Other alternative fuels (methanol, race-specific blends) should be verified for compatibility before use.
Who This Is For
This kit fits a few common build profiles. If you're running a turbocharged SR20DET, KA24DET, or RB build and the factory fuel pressure regulator isn't keeping up with injector demand, this is the upgrade. If you're switching to E85 or planning to, the V2's E85-compatible construction means you're not replacing the regulator again when you make the fuel switch. If you've been chasing rough idle, hesitation, or inconsistent power and you've ruled out other fuel system issues (pump, injectors, filter), an adjustable regulator with a gauge gives you the ability to actually verify and dial in fuel pressure. If you'd rather buy a complete matched kit than source individual components, this saves you the parts-hunting hassle.
This kit is not necessary if you're running a completely stock setup with stock fuel demands. The factory regulator is sufficient at factory power levels.
What's in the Box
- 1x ISR Performance Fuel Pressure Regulator V2 (E85 compatible, bypass style, includes 1x -6AN plug with O-ring)
- 1x ISR Performance Fuel Pressure Gauge (0-100 PSI)
- 1x ISR Performance Fuel Rail Adapter
- 2x ISR -6AN ORB to 7mm Barb fittings
- 1x Mounting Bracket
- 4 feet of E85-compatible Fuel Hose
Installation Notes
Professional installation is recommended for anyone not already comfortable with fuel system work. The regulator installs into the fuel return line and connects to the fuel rail via the included adapter and fittings. The gauge mounts to the regulator for direct pressure readings, and the mounting bracket secures the regulator to the engine bay or chassis at a location with clean hose routing.
Standard fuel system safety procedures apply: depressurize the fuel system before disconnecting any lines, disconnect the battery, and work in a well-ventilated area away from ignition sources. After installation, fuel pressure should be set per your engine's tune specifications and verified across the operating range before driving. Initial baseline pressures vary by platform and build, so reference your tuner's recommendations.
Product Details
Brand: ISR Performance
Product: Fuel Pressure Regulator Kit V2 (E85 Compatible)
Part Number: IS-FPRKit-V2
Regulator Type: Bypass style, adjustable
Version: V2 (E85-compatible internals and seals)
Fuel Compatibility: Gasoline, race fuel, E85
Engine Compatibility: Nissan KA24DE, KA24DET, SR20DE, SR20DET, RB20, RB25, RB26
Vehicle Applications: Nissan 240SX (S13/S14), other Nissan chassis using KA, SR, or RB engines
Gauge: ISR Performance 0-100 PSI fuel pressure gauge (included)
Fittings: 2x -6AN ORB to 7mm barb, 1x -6AN plug with O-ring
Fuel Hose: 4 feet, E85 compatible
Fitment: Universal (within listed engine platforms)
Assembly: Assembled in house by ISR Performance
Included: Regulator, gauge, fuel rail adapter, fittings, mounting bracket, 4 feet of fuel hose
Key Benefits: Complete matched fuel pressure regulator solution, bypass design for stable pressure under varying demand, full E85 compatibility throughout the kit, adjustable for tuned fuel pressure targets, single-package convenience over piecing together individual components