Engine device

An engine device comprising:

• an engine capable of coping with both a premix combustion mode in which premixed fuel obtained by mixing gaseous fuel with air in advance is supplied into a cylinder and combusted and a diffusion combustion mode in which liquid fuel is injected into the cylinder and combusted;
• a gas supply device configured to supply the gaseous fuel into the cylinder in the premix combustion mode;
• a pilot injection device configured to inject the liquid fuel into the cylinder in the premix combustion mode;
• a main injection device configured to inject the liquid fuel into the cylinder in the diffusion combustion mode;
• and
• wherein the engine device is configured to initiate a failure diagnosis process in the pilot injection device, the pilot injection device configured to inject a liquid fuel while the engine operates in the diffusion combustion mode during the failure diagnosis process, and the failure diagnosis process based on a pressure difference between a first maximum pressure detected in the cylinder and a second maximum pressure detected in the cylinder, the first maximum pressure based on a first amount of the liquid fuel injected from the pilot injection device and the second maximum pressure based on a second amount of the liquid fuel injected from the pilot injection device, the second amount of the liquid fuel greater than the first amount of the liquid fuel.