I once worked on some engine modules that are rented in quantity for generating power or pumping stuff into/out of ships.
Said modules comprised one Deutz air-cooled Diesel engine with mechanical fuel injection, air start, and a fuel tank all mounted in a tube frame that made them easy to handle and stack. No electrical parts whatsoever. Attach a pump or generator to the flywheel, start 'em up, and just keep putting fuel in the tank.
I don't think you could make a new one today, because current emissions requirements pretty much demand computers.
Mike Halloran
Pembroke Pines, FL, USA