Low Pressure Lock-Off Solenoid

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.

The Low Pressure Lock-Off (LPL) solenoid is a normally closed, solenoid valve. The LPL is mounted in the Intermediate pressure line. The PCM controls LPL solenoid operation. The Powertrain Control Module (PCM) energizes the LPL solenoid only when engine cranking or running is detected. Anytime the engine is stopped the PCM de-energizes the LPL solenoid to stop fuel flow. The PCM operates the LPL and the High Pressure Lock-Off (HPL) solenoid at the same time except at ignition ON. During ignition ON only the HPL is opened, while the LPL remains closed, to charge the fuel system with CNG. The LPL is supplied fuel from the HPR with fuel pressure between 110-210 psi (758-1448 kPa). The outlet of the LPL supplies the Low Pressure Regulator (LPR) with fuel.