Controller for a fuel supply system

A controller for a fuel supply system that includes a hydrogen engine configured to use hydrogen gas as fuel, a fuel tank configured to store the hydrogen gas, a hydrogen pipe used to guide the hydrogen gas from the fuel tank to the hydrogen engine, a shut-off valve arranged on the hydrogen pipe and configured to shut off supply of the hydrogen gas from the fuel tank to the hydrogen engine, and an injector configured to inject the hydrogen gas into the hydrogen engine, the controller comprising:

• processing circuitry configured to control the shut-off valve and the hydrogen engine, wherein
• in response to an operation that requests to stop the hydrogen engine performed by a user of a vehicle including the fuel supply system, the processing circuitry is configured to execute a failure determination routine,
• the failure determination routine includes:
• executing a control that closes the shut-off valve and then monitoring a decrease rate of pressure of the hydrogen gas at a downstream side of the shut-off valve while keeping the hydrogen engine running;
• and
• determining that the shut-off valve is not properly closed based on the decrease rate being less than that when the shut-off valve is properly closed, and
• the processing circuitry is configured to stop the failure determination routine in response to a stop of the hydrogen engine caused by an engine stall during execution of the failure determination routine.