trojan 164a

I just purchased an old trojan 164-a rear wheel steer loader with a 2 cycle detroit diesel in it. when I got it home and unloaded it off the trailer it ran fine until I parked it (about 30 mins) I was checking it over and smelled gas in the fuel tank? my question is will it damage the engine to keep running it on the rest of the gas thats in the tank and then put fresh diesel in?

-thanks