Methods and systems are provided for depressurizing a fuel pressure regulator during engine cold start and varying fuel injection pressure after cold start in a gaseous-fueled vehicle. A mechanical pressure regulator may be modified to include valves which may be controlled to depressurize a reference chamber of the regulator when gaseous fuel injection is inactive (e.g., before and during cold start), and to regulate the pressure of gaseous fuel to varying pressures based on electronic pressure feedback and engine operating conditions when gaseous fuel injection is active. In one example, the pressure in the reference chamber of a pressure regulator may be varied by controlling valves to flow gaseous fuel into the reference chamber, and then controlling the valves to exhaust the gaseous fuel from the reference chamber, for example to a fuel vapor storage canister.