MS3 Fuel Pressure Failsafes

MS3 Fuel Pressure Failsafes

When you’re pushing your engine to the limit, a sudden loss of fuel pressure can spell disaster. With the fuel pressure failsafe feature in the MS3X and MS3Pro, losing pressure doesn’t have to mean losing your engine. The ECU can detect fuel pressure drop and automatically trigger a limp-home safety mode to protect your build.

Here’s how it works:

  • The MS3 will activate a spark cut first, allowing fuel to continue flowing to cool the engine.

  • It will then cut fuel completely once engine RPM and load fall to a safe level where detonation risk is minimized.

This sequence helps protect both power and reliability, even in emergency conditions.

Step 1: Install a Fuel Pressure Sensor

To use this feature, you’ll need a properly calibrated fuel pressure sensor. Optional Sensors: 0-100 PSI or Combo Temp and Pressure

  • Go to Advanced Engine → Generic Sensor Inputs.

  • Configure the sensor input pin (or remote CAN input).

  • Input the calibration data for your chosen sensor.

  • Scale the pressure values in kilopascals (kPa). You can use either absolute or gauge-type pressure sensors.

Step 2: Configure Fuel Pressure Settings

Next, set up how the ECU interprets fuel pressure readings:

Navigate to Fuel Settings → Fuel Pump and Pressure and configure:

  • Whether your fuel pressure regulator is vacuum-referenced or constant pressure

  • Base fuel pressure value

  • Which Generic Sensor is being used for fuel pressure

  • Whether the sensor is absolute pressure or gauge pressure type

Step 3: Enable Fuel Pressure Safety

Now activate the failsafe function:

  • Go to Fuel Settings → Fuel Pressure Safety.

  • Turn the feature ON.

  • Set the allowed pressure drop before failsafe activates.

  • Configure the delay time (long enough to avoid noise or jitter in the signal, but short enough to respond quickly).

Step 4: Configure AFR Safety Settings

Finally, define how the ECU transitions between spark cut and fuel cut:

  • Navigate to Fuel Settings → AFR Safety.

  • Set the duration of the spark cut before full fuel cut.

  • Configure the safe conditions (RPM/load) where fuel can be restored.

Conclusion

With this setup, the MS3X and MS3Pro can actively monitor fuel pressure and protect your engine against catastrophic fuel delivery failures. By installing a fuel pressure sensor and properly configuring these menus, you’ll have peace of mind knowing your ECU will safeguard your engine automatically.