A method for supplying fuel to an engine is disclosed. The method may include regulating a gas admission valve disposed between a gaseous fuel line and a cylinder intake port to reduce flow of gaseous fuel to the cylinder. The method may also include closing a shut-off valve disposed between a gaseous fuel reservoir and the gaseous fuel line to restrict flow of gaseous fuel from the gaseous fuel reservoir to the gaseous fuel line. Further, the method may include actuating an inert gas inlet valve disposed between an inert gas reservoir and the gaseous fuel line to supply inert gas to the gaseous fuel line and flush the gaseous fuel in the gaseous fuel line into the cylinder via the gas admission valve. Additionally, the method may include closing the inert gas inlet valve to restrict supply of inert gas to the gaseous fuel line.

A gas supply system, having a gas regulating station for supplying an engine with gaseous fuel and a double-walled gas line extending from the gas regulating station to the engine, which comprises an inner and an outer pipe, in a gas fuel operating mode the inner pipe is flowed through by the gaseous fuel towards an engine-side end of the double-walled gas line, an inert gas purging line, and a first shut-off valve assigned to the inert gas purging line. In a purging mode inert gas can be fed to the outer pipe at the gas regulating station-side, which inert gas flows through the outer pipe in the direction of the engine-side end of the double-walled gas line, where it passes into the inner pipe and flows via the inner pipe towards the gas regulating station-side end of the double-walled gas line.

Various methods and systems are provided for a multi-fuel capable engine. The system includes a liquid fuel system to deliver liquid fuel to an engine, a gaseous fuel system to deliver gaseous fuel to the engine, and a control system. The control system can control and test the liquid and gaseous fuel systems.