Maybe you guys can help as I am at my wits end. When I drive my car in the rain it stumbles and hesitates terribly. I changed the pickup coil, rotor,ignition control module, cap,wires,map sensor. The car has a 305 t.b.i. , automatic trans. When I spray water on the closed hood near the base of the windshield it starts stumbling immediatly. I've checked the electrical plugs and can't find any vacuum leaks. Help !!!

 

You mentioned the pickup coil , but did not mention the ignition coil , did you change that as well ? You problem sounds spark related and since you mentioned everything else , I figured I'd ask .....

 

Did not replace ignition coil

 

How do you check the ignition coil?

 

Normally , the electrical checks are done with an Ohm meter , but in your case since the car runs we know the coil has not lost continuity . In your case , we would be looking for "insulation breakdown" which would cause the coil to loose spark when wet . Take an empty windex bottle and put some water in it . With the hood open and the engine running , carefully spray a small amount of water at the coil . Does the engine stumble or quit , if so replace the coil . If not , spray the distributor a bit , if it quits (and the wires are seated properly) then the cap is defective (remember , "brand new" is NOT "proof" of perfect working components , LOTS of new stuff shows up defective these days) .....

 

I tried the water spray bottle on the distributor and coil , it wasn't affected at all. I did gently spray water on the base of the windshield. I started at the drivers side and worked over to the passenger side. When I sprayed on a thick wire loom located just beside the air conditioner box the car started to stumble. I followed the loom down and it goes behind the plastic interwheel well and plugs into another harness that goes into the interior of the car. I sprayed the plug and it immediately stumbled. I think I found the spot but I don't know why it is stumbling, still puzzeled.

 

In terms of what those connectors do, I couldn't tell you. But it's clearly stumbling because electrical components are getting wet. If you take some electrical tape and wrap the harness/connectors up good then you shouldn't have a problem.

 

Umm , Not so fast yet with the electrical tape ......

If the OP has found a connector that causes the engine to quit when wet , it would be best to disconnect that connector and clean out the inevitable gunk that's in there causing the connection to fail with the application of water . maybe after a good clean solid connection is established he could consider insulating the connector , but to seal it in with the water & crap that's in it now will allow the corrosion to totally finish off the connector .

 

Good point, I should have been more clear (instead of assuming the part had been cleaned out lol)

 

I tried to pull the connector apart but can't do it. It's a large connector and has about a dozen wires in it. Do you have any idea what this connector goes too

 

I finally think I found the problem, after pulling the plastic inner wheel well cover loose I was able to get axcess the the wires. I was able to disconnect them from the inner car body, once I was able to see the plug I could see three wires with the coating rubbed off. I applied liquid wire coating on them , resealed the wires to the housing and reattached it to the car. My fingers are crossed and I hope this works.