Wet Weather Hard start on Express 3500

[Cessnadriver]

A friend of mine has a 2001 Express Van 3500.
Recently, after the first heavy rain since he got the van, it was extremely hard to start.
He tells me it sounded like the plug wires were crossed.
After getting it to start, it was VERY rough, and if he touched the throttle, it would die.
He let it "rough idle" for close to an hour and got it to run well enough to drive. It ran rough for a while longer, an hour or so and straightened itself out.
Any ideas or experience on why moisture would cause this would be appreciated.
Thanks

[Craig013500]

I had exact same problem. There is a factory service bulletin on it. Good news is its simple. If you pull off the distributor cap you will find moisture. Dry it out. Under the rotor, off to one side, there is a small screen that the distributor "breathes" through. It is clogged. Take a small screw driver or ice pick and remove screen. Problem solved. By far the hardest part is getting the engine cover off. The first time I just dried it out and put it all back. Ran great but problem returned with first good rain. Screen removed no problems 25000 miles

[MT-2500]

Originally Posted by Craig013500

I had exact same problem. There is a factory service bulletin on it. Good news is its simple. If you pull off the distributor cap you will find moisture. Dry it out. Under the rotor, off to one side, there is a small screen that the distributor "breathes" through. It is clogged. Take a small screw driver or ice pick and remove screen. Problem solved. By far the hardest part is getting the engine cover off. The first time I just dried it out and put it all back. Ran great but problem returned with first good rain. Screen removed no problems 25000 miles

Welcome to AF.
Thanks for the info.
But this post is 5 years old.
Always check date on a post and if it is old let the dead rest in peace.

[Craig013500]

So sorry dude but I dont care if its 50 years old. It just happened to me and if I had seen this post it would have saved me several hundred dollars and lots of heartache. This aint a chatroom, its a place to get information.

[MT-2500]

Originally Posted by Craig013500

So sorry dude but I dont care if its 50 years old. It just happened to me and if I had seen this post it would have saved me several hundred dollars and lots of heartache. This aint a chatroom, its a place to get information.

I am not Dude.

AF forum rules and regulations say not to reply to old post.
Read them and weap.
MT