Methods and systems for fuel rail pressure relief

A method, comprising:

• delivering fuel to an engine cylinder via a port injector while maintaining a direct injector disabled;
• during a first condition, reducing pressure at a fuel rail of the direct injector by opening a pump relief valve while maintaining the direct injector disabled;
• and
• during a second condition, first reducing pressure at the fuel rail of the direct injector by opening the pump relief valve while maintaining the direct injector disabled, and then further reducing the pressure by intermittently enabling the direct injector.

A fuel system comprising:

• a first fuel rail coupled to a direct injector;
• a second fuel rail coupled to a port injector;
• a high pressure pump coupled to a fuel line leading to the first fuel rail;
• a fuel tank;
• a low pressure fuel pump coupled to the fuel tank;
• a pump relief valve coupled upstream of the high pressure fuel pump, between the high pressure fuel pump and the first fuel rail, wherein the pump relief valve is configured to maintain a fixed fuel pressure in the first fuel rail;
• and
• a controller including non-transitory instructions for intermittently activating direct injection only if a further pressure relief below the fixed fuel pressure is requested.