Hi, I just bought my 240 a couple of months ago and everytime I leave it outside overnight when it is raining then it starts idling very roughly and stalling the next day. I thought it was water seeping into the gas tank but it starts running fine after a couple of days. Anyone out there who thinks they can help me with this?
Thanks. 
Change your spark plug wires and I bet you’ll have it solved!
You might as well do a full tune up at that time too, sounds like it may have been a while.
Good luck.
Theo
It’s probably the carb.
cal, not going to play nice? :lol:
may also want to look at the distributor cap/rotor… along with theo suggestion…
One way we used to do it in the garage. Start up the car and spray water at the electrical parts to see if it affects how it runs. (Usually ignition wires, rotors, caps)