Q: Truck wont start in the rain

This could be an ignition coil that may be starting to fail, but is more prevalent in the cold weather or rain. Generally, this is common when the coils begin to break down and heat cycling occurs, however the opposite can be true as well when it comes to cold and moisture as you may be experiencing.

Ignition coils are prone to this type of erratic functioning or heat cycling when they are beginning to fail due to the temperature fluctuations under the hood which ultimately cause them to shut down causing the car to only run after cooling down for 30-40 minutes. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil’s ability to function. This process will repeat itself continuously until the coil ultimately fails completely and must be replaced. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your ignition system.