I have a 1998 Dodge Ram 1500 5.9 and it runs rough in the rain and then eventually doesn't run at all. The code comes up as the crankshaft position sensor so I replaced it. Still having the same problem. My check engine light came on again last night during the rain and it's coming back as the position sensor again. This only seems to happen in the rain. I've done a whole tune up to the thing and still it runs rough when it rains for more than one day straight. I can't seem to figure out what's wrong with it and neither can anyone else that I ask. Please help!

 

Where did you get your crank sensor from? What brand?

Did you replace your plug wires? Distributor cap?

 

I got it at autozone and yes new wires, plug, cap, crankshaft sensor, ignition coil and one other thing I can't remember right now.

 

Autozone? hhhmmm.......

Usually, poor running in wet weather is plug-wire related..... Is the seal at the back of the hood still in place on your truck? The weather guard over the connectors on the PCM? Apparently, something is getting wet, and causing issues..... if water is dripping onto the distributor, (lack of the seal at the back of the hood) that is likely going to cause some trouble......

I would be tempted to wait until dark, get a spray bottle, with just water in it, start the engine, and that start spraying various things.... See if you can duplicate the issue, or perhaps, see the light show from wherever the spark is going to arcing around. (VERY visible at night.....)

 

How's the seal across the of the hood?... old, compressed?... could rain be running onto the distributor?

 

Does it matter if it's a new cap? I got a new cap and it's still doing it. I'll try doing some of that spraying later tonight when it gets darker to see if anything shows.

 

If enough water gets on it, no, it doesn't matter. While its still light out, check the connectors at the PCM, should be like a rubber flap over them, that sheds the water away from the connectors.

 

I am just wondering if somehow one of your O2 sensors is shorting and telling the PCM to do something? "Codes" can sometimes be misleading at times also. It's an easy test...start the truck and grab your water hose and spray water around the O2 sensors.

Report back.

 

Did you clear the fault code after you replaced the sensor? I think the water issue is something different and not related. If the sensor stopped working there would be no spark. And don't spay water on a hot motor, The steam will get in the distributor cap. This may be the issue if the seal is leaking.