Hard starting when damp

[Bob L]

Lately if it rains overnight or is very foggy my truck just cranks and no start. If I just bump the key it will start sometimes in a couple tries but lately it is taking a few minutes and many tries. Once it starts it runs fine and idles fine and doesn't act like wet ignition at all. After driving even in rain or puddles it runs fine and starts fine till it sits for a long period when wet. I have sprayed the wires and cap with a trigger bottle of water while running and no miss fires at all.
Truck is a 98 4.3 and runs great except for this. Any ideas besides throwing cap ,rotor and wires at it?

 

[1994_GMC]

maybe a vaccum leak? intake gaskets maybe

 

[Tdean91491]

Check your distributor cap sometimes moisture can get in and cause problems with the firing there.

 

[Crazydavez28]

Mine does this all the time. It tries to run backwards once the exhaust is loaded with fuel vapor.

I am going to try a new distributor on my high mileage 5.7 . I think crankcase moisture is getting in thru the bushings. Just bought a brand new distributor for my 7.4 and it was $60 on RockAuto came complete ready to go too.