No start under damp conditions

[Brad Kline]

I own a 1989 240 GL with 126,000 miles that starts and runs great under most operating conditions. When the weather is dry either in summer or winter irregardless of temperature it starts right up. If however it has been wet outside it will just crank and crank sometimes one or two cylinders will fire but it won't start. Once the weather clears and things dry off a bit it starts right up again. It runs fine otherwise and once started I've driven it through drenching rains and it won't miss a beat.
I've also noticed that if the engine is warm and its damp outside it will start most times. It seems that engine heat is keeping some component dry and allows it to start.
Here's what has been replaced, new sparkplugs, sparkplug wires, new distributor cap and rotor. New crankshaft position sensor. None of these parts has had any impact whatsoever on the non start under damp conditions problem.

I'd appreciate any ideas or suggestions to remedy this situation.

Thanks Bradley Kline

[cosmiclobster]

This, IMHO, is a "moisture in the distributor" problem!
There should be a rubber seal beneath the distributor cap that keeps moisture (and dust etc) out. If there is a tiny bit of moisture inside the distributor cap, the engine WILL NOT start.
This can be tested easily during one of the times that it won't start.
Remove the cap, take a nice clean dry towel (or sacrificial washcloth) from inside the house and wipe the cap dry. If you can see water droplets on the rotor and other places inside the area where the caps sits, you will need some compressed air (like from a can) to blow the water out of there.
I'll bet dollars to donuts that this is your problem!!!