Won't start when wet out....

I'm looking for ideas on things to check on my XJ. If it's been sitting for a few days and it's been wet outside, it just cranks and won't start.... Once it dries out and warms up it's fine... It doesn't seem to do it if I'm driving it on a daily basis and the engine has been warm a couple of times during the day.

The specs:

'88 XJ Wagoneer
'93 4.0 HO that was swapped in, but with the majority of the '88 Electronics still in place.
Manually shifted AW4 via a 4-position switch and NP242 T/C (not that these should make a difference I don't think).

I just got this thing and this is the first time it's personally happened to me. The previous owner told me about it but said that he couldn't replicate the problem to troubleshoot it, even with a garden hose...

Any ideas????


Thanks,

Jeremy
http://www.iowa4wd.com/

You will need: Brake Cleaner and a tube of silicone dielectric grease.. (not silicone sealer)

use some brake cleaner and clean the dirt and grease out of the main harness connector that sits above the brake booster/master cylinder. take it apart and flush it good
after it is fully clean... take the grease and smear a layer all over the face the connector and in the back of the terminal ports

that should fix it. The TPS wires sit next to each other there and with dirt there, when it gets wet, there is enough continuity to cause a no start.

Try a new distributor cap. Gunk or a small crack can play havoc with a cap. I've seen condensation on the inside of distributors when the crank case ventalation is restricted.

Cap would be my first choice too... had a 66 mustang that drove me nuts for about 5 months or so. Pulled the cap one morning and it was sweating inside. Crack was invisible.

Okay, I'll pull the cap and give that a try and then it doesn't sound like it would hurt to clean up the main harness while I'm at it...

Any other ideas? I'm heading out to try these right now...


Thanks,

Jeremy
http://www.iowa4wd.com/

reason I didnt mention cap and wires, is that he said that a test with a water hose showed nothing.... cap and wires will show up then...usually.

Cap was bone dry inside... Darn, it's not going to be that easy

I took the wiring harness apart that you had mentioned. It seemed pretty dry inside and was already packed with tons of dielectric grease. It looks like the previous owner also suspected this connection...

Here's where it gets weird:

I took the connector apart and reassembled. Nothing changed... I messed with all the wires in that area for a while, then I got a short fire every couple of cranks but it still wasn't starting. I started dissasembling that connector again and decided to see if it would still "hit" like it was trying to do with the connector completely disconnected. It continued to do the same thing but still wouldn't start and run. I started giggling wires in the bulkhead connector that appears to go the back of the main fuse box below the brake booster and it fired up, but then died because the connector about the brake booster was still disconnected. I hooked the connector above the brake booster back up again and it fired up and stayed running this time. It appears that something is shorting out in that main connector below the brake booster to me...

Any suggestion on how/where to start troubleshooting in that area? Does it sound like I'm on the right track?


Thanks,

Jeremy

Make sure the master cylinder is not leaking on that cable bundle, it will eat for lunch. On my 98 there is a big connector down by my left foot where all those cables connect. When I was putting in my factory fog light add on kit I found that the connector box that is held together by a single bolt in the middle and it was falling apart. I kept loosing my instruments, clock, radio settings. I disassembled and cleaned it then bolted it back together, fixed a bunch of problems.

Yeah, I think that's going to be the next one that I attack. I think I'll just start unplugging every connector under the hood one at a time, cleaning them up and putting some dielectric grease in them. Is there anyway of "waterproofing" some of those connectors externally while I'm at it?

kee said:

Yeah, I think that's going to be the next one that I attack. I think I'll just start unplugging every connector under the hood one at a time, cleaning them up and putting some dielectric grease in them. Is there anyway of "waterproofing" some of those connectors externally while I'm at it?

Click to expand...

Not that I can think of off hand unless you want to use outside rated shrink tube, has a sealer that seeps out of the ends when you apply heat but I don't think it would work well with the big connectors/small wires on the XJ. The dielectric should do the job pretty well.

I had the same problem with my dodge 2.5l same engine as jeep. I replaced the cap and rotor and that fixed it. I think that it was just worn down.