rain = no go

[claptonfan]

I think i might have posted about this before. I searched but didn't come up with anything, so i thought it wouldn't hurt to ask again. I've been having the problem of my car stalling at idle when its raining or really humid out. I replaced the distributor cap and rotor, thinking that water might have been getting inside, but it didn't help at all. It usually starts fine, but idles rough at first, then starts to stall once it warms up a bit. I've tried adjusting the idle mixture, but it doesn't help much. What could be causing this problem? The engine in question is 200 in a '65 mustang.

 

[simon]

old paper air cleaner elements may swell up in humid conditions so much that the fuel air mixture will actally suffer, hence the rough idle and stalling.

Did you notice any differences with the air cleaner removed?

the only other thing I could think of would be some weird ignition demon lurking in your electrical system.

 

[Ronbo]

Is the carb heater in place? My 300 acts wierd when it rains and the temp is cold. Could be the same type of situation.

 

[claptonfan]

i haven't noticed any difference with the air cleaner off, and the heater plate is in place. I had thought that this was limited to rain and cold weather, but its been pretty warm lately (50-60) and it still happens.

 

[MustangSix]

It could still be a moisture problem.

Grab a can of Water Displacement Formula Number Forty (WD-40) and spray down the inside of your cap and distributor. Wipe with a dry cloth. Do the terminals on the outside too and the spark plug boots.

 

[Guest]

Don't overlook your coil as well. I've found that to be a cause of problems when raining in another vehicle.

 

[Anonymous]

I would lean towards ignition problem. things like bad plug wires or coil wire or some other area where water is causing a power loss. Old plug wires are notorious for causing hard to track problems like this. On a dark wet night pop the hood and look for small blue arcing--under the hood not area57.

 

[BIGREDRASA]

There's also a main electric harness connector at the firewall, that can get humid and cause problems. Find every electrical connector and give it a shot of WD-40.

 

[claptonfan]

thanks everyone. i've sprayed a bunch of stuff with wd-40 and taped up some wire that was exposed. now i've just got to wait until it rains.

 

[Anonymous]

Also you can try di-electric grease inside the distributor cap, on it's wire connections and on the wire plugs as they seal at the plug. This prevents some arcing and does not impede the normal flow of trons at all.

It sounds like the moisture is the problem...as it only occurs in rain.

New wires are a cheap investment. Try them as well.

Steve-O

 

[claptonfan]

just an update in case anyone else is having a similar problem: after taping up some wires and spraying wd40 on everything i could find, the car ran fine in the rain. thanks for the tips everyone, this has made my life much, much easier.