Method of controlling injection pressure level in unit injectors

A method of controlling an injection pressure level of fuel within a unit injector having a first spill valve, wherein the first spill valve is configured to allow return of a first portion of the fuel from the unit injector to a low-pressure fuel manifold, the method comprising:

• providing a second spill valve in the unit injector connected in parallel to the first spill valve, wherein the second spill valve includes at least one of a controlled orifice or a fixed orifice;
• delivering fuel to the unit injector, with the first spill valve being in a passive state, to facilitate delivery of the first portion of the fuel to the low-pressure fuel manifold;
• actuating the first spill valve to an active state, and facilitating blockage of flow of the fuel to the low-pressure fuel manifold such that the fuel within the unit injector is maintained at about the injection pressure level;
• and
• actuating the second spill valve to the active state at least concurrently or prior to the actuation of the first spill valve to facilitate delivery of a second portion of the fuel to the low-pressure fuel manifold to limit the injection pressure level within the unit injector.