Engine was running fine and shut it off 5 min. Tried restart and engine cranks but won't fire. Dual tanks 1 new fuel pump.Switch tanks still no start, tried next day, runs fine???????

Step #1 in any automobile diagnosis is "Isolate the system"
Switching fuel tanks may have seemed like a good idea, but it did not definitively determine whether the the fuel is getting to the fuel rails, so you are no closer to eliminating the fuel devery system than you were when the engine died.
If it does it again, you should do the easiest things first.
Pull a spark plug wire and check to see that you have good spark reaching the spark plugs. Good spark will eliminate the entire spark control system.
Only if you have good spark should you suspect a "part-time " fuel system problem. The Fuel delivery system can be eliminated if actual fuel pressure is checked at the fuel rail. (although you could still have injectors not firing for one reason or another)
You are losing one of these systems. (spark or fuel) only once you have determined which one, can you continue diagnosis to pinpiont the failure.