Dodge no start when it rains

[enginetune]

Just like the subject says, I get a call in the morning while it's raining. It's a friends truck, '99 Ram with a 360, says it sat all weekend and it rained Sunday night. It just cranks. I told him to check for spark and call me back but he never did. I read a couple posts about caps and wires, which I would expect but, he says he can't here the fuel pump as usual. Is it possible for the ignition module to fail? I know of a few others with the same problem but they have other cars to drive and don't really care to have it looked at. All the '99 tune up parts are less than 6 months old to try and fix this before winter but seemed to have no effect. Anyone got any info or maybe a Dodge TSB on this problem? Thanks.

[theFREAKnasty82]

Have him check the air intake snorkel going to the throttle body; if there's moisture, that'll more than likely cause a no-start when it rain. And the ignition module is inside the PCM, so if that is gone (which I doubt) then you replace the PCM. First check for moisture.

[enginetune]

I see what you mean about the module so I'll leave that for now. What does moisture in the intake have to do with a no start? My guess without looking is it effects the mass air sensor. And how much is considered enough to cause a problem? A better question is how to safeguard against it. I will be looking at it this weekend so I need to prepare a little.

[theFREAKnasty82]

just FYI, that truck doesn't use a mass air flow sensor, if anything it uses a MAP to measure intake manifold vacuum and only reads vacuum, not moisture BUT, water could alter the reading of the MAP. Just a possiblity.

[enginetune]

I fail to see how a MAP will cause a no start. I think it may cause a stall after start by incorrect fuel rate. Just cranking the engine probably won't supply enough vacume to make a difference. BUT, stranger things have happened. I know of an Olds that had a faulty O2 sensor that caused a no start. By rights it doesn't do anything 'till it hits closed loop, replacing it fixed the car. I'll know more about this Dodge thing soon enough, even if I have to soak it with a hose.

[isoceles]

I have a '99 Ram also, same thing. Sit all weekend, go to start it after a Sundaynight rain, no start.

Funny thing is, if it rains tonight it will start tomorrow, seems like only won't start after two full days of sitting. The other thing is, I always park on a forward slant. When I park on the flat or listing, it could rain like a cow peein on a flat rock for a week, and it'll start right up.
All I can tell tell you is if I hear rain for the weekend, I park in my flat driveway, or I pull in to my spot I usually back into. Curious to know if your friend parks on an angle too?