Fuel Pressure Regulator Diagnosis: Notes

WARNING: This page is about a different variant/trim than selected.

The Fuel Pressure Regulator graphing procedure offers valuable information on regulator performance by comparing desired and actual fuel rail pressure. An almost perfect comparison between fuel rail pressure and desired fuel rail pressure is found on low mileage engines. A minor ripple is acceptable behavior for the fuel rail pressure regulator and is seen on high mileage engines. A "shark tooth" fluctuation in fuel rail pressure indicates a sticking fuel pressure regulator.

At engine start, the engine control module (ECM) commands fuel pressure regulator 2 to control fuel pressure at idle. The engine will remain in this mode if the fuel temperature is below 15°C (59°F) or until fuel pressure regulator 2 adapts (which occurs at higher engine loads) or until fuel temperature reaches 60°C (140°F). The adaptation is a learned factor that adjusts fuel pressure regulator 2 current to compensate for manufacturing tolerances and component aging. Once the adaptation is complete, the vehicle will use fuel pressure regulator 1. The fuel pressure regulator 2 adaptation will attempt to run again at the next drive cycle. The actual and desired fuel pressures should be within 690 kPa (100 psi) during all engine operating modes.