Hello Charles,
No need to worry, these units are designed to work submerged and flooded with fuel.
In regards to starting the engine...............for best results, remove all spark plugs, crack loose each injector line at the injectors, and crank the engine with full throttle. as fuel emerges from each injector line, tighten it up. When all are tightened, crank a little more then install all spark plugs and start the engine. Otherwise, the engine will start without any dis-assembly or spark plug removal, just crank at full throttle. This method is much harder on the starter and the battery.