1993 Nissan 300ZX I dont know what the porblem

My car have this porblem. Went it is rainning hard outside on the car the act like is dead, and went the a summing day and dry the car worked like it ever have a porblem. Went it rain on the car, cant start the car no crank are sound like the engine is dead. And after the rain stop I try to start it still didnt work but after it all dry up, you can start it up like nothing have happen to it. I just to know how to fix the porblem