I am a real novice but want to learn. I just bought an old 150 wiht 244225 miles on it. It cranks and runs fine EXCEPT when it rains. The seller said he also had the problem and suggested changing the plug wires. Is that where I should start? Thanks.

 

At that mileage, sure couldn't hurt. I'd suspect though you're getting moisture into some part of the ignition system. If it was me, I'd get some water dispersant (like LPS though there are other brands) and take apart every electrical connection I could get apart and spray them and reassemble. If that's your issue, I'd suspect that would fix it. There's also the chance you have some wiring with broken or missing insulation that's grounding when wet, so keep your eyes open for that too.

Good luck.

 

Full ignition tuneup - spark plugs, spark plug wires, distributor cap, and rotor.

 

Thanks guys! I checked all the connections and found the wire to the coil had a lot of corrosion and then discovered the rubber seal where the hood closes was leaking right above the coil and condenser. I changed the condenser and cleaned the coil connection and (hopefully) repaired the rubber seal. It now starts when it rained; however, it was not a hard driving rain. I put it under the hose for quite a while when it was cold and it started right up. Thanks again!