GM-GMC: wont start after it rains, silicone grease, heavy rain

Question
We have a '98 K1500 pickup. 3 times this past week the truck would not start after heavy rain. Replaced the rotor, distributor, plug wires, & fuel filter - none solved the problem. Truck will start & run fine apparently after it "dries out." Have read through several online forums with many different possible causes for different vehicles. Any experience with this type of problem? Any ideas or suggestions you could offer would be greatly appreciated!

Answer
My diesels don't have ignition systems and my Toyotas merely short their alternators after a heavy rain!

I would say that you changed all the items normally associated with this problem.  I would be that you have water getting into the wiring and shorting wires and/or connectors out until they "dry out."

You might check all the wiring harness connectors and reapply some silicone grease to try and keep water from getting in.

I apologize for not being able to provide more help.