High Pressure Regulator (HPR)

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The HPR is supplied with fuel from the CNG fuel tank at up to 24,821 kPa (3,600 psi) through high pressure stainless steel lines. The HPR reduces fuel pressure to between 758-1,448 kPa (110-210 psi). The outlet of the HPR is the Intermediate pressure stage. Fuel flows out of the HPR and into the low pressure lock-off (LPL) solenoid. The pressure drop within the regulator causes fuel temperature to drop. In order to prevent HPR freeze-up, the HPR is connected to the vehicle engine cooling system. The HPR contains an over-pressure relief device (PRD) which will not allow pressure above 1,896 kPa (275 psi) on the output stage of the HPR. The PRD is removable in order to allow the installation of a pressure gage for diagnostic purposes. The HPR has an internal, serviceable 40-micron filter. This filter must be serviced periodically. Refer to High Pressure Regulator (HPR) Filter Replacement for replacement procedures.