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Won't start...only when it rains

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6K views 25 replies 13 participants last post by  gravitysucks 
#1 ·
My 94 D90 has a little problem. It always starts, except when it's raining. I can run through deep water, drive in the rain (so long as it was running when it started raining), but when rain starts...the little guy will crank and crank and crank...but won't start. I think I've checked everything...but am obviously missing something. Any help would be appreciated. Again, it only has starting problems while it's raining. About 30 minutes after the rain stops, it starts with no problems.

Again...any help would be appreciated.
 
#3 ·
It has new rotor/wires and I did change out the coil. But, if it was simply one of those shouldn't I expect it to always have the problem whenever it contacts water? I can run through deep water...shut it off and it'll fire right back up. I'm not kidding when I say it doesn't start in the rain. If it's raining and I shut it off, it won't start again. It has me baffled because it only happens in the rain. Is there anything potentially under the dash? I have the fiberglass hard top and it does leak a little, but nothing ever really seems to get wet.

An example...it's been raining here for a few days. I parked the Rover just after it started raining hard and 20 minutes later it wouldn't fire. The rain stopped about 30 minutes ago and it starts right up.
 
#4 ·
My 94 did the same thing even after I replaced all wires, the rotor, and the plugs. Only when it was raining and I first went to start the car would I have this problem. Then I realized that I was pumping the accelerator when I was starting it (old habit) and was flooding the engine. If I don't touch the accelerator is starts fine now. You probably aren't guilty of this little piece of ignorance, but I throw it out there anyways, just in case...
 
#5 ·
Well,
Get back to basics...it takes air, fuel and fire to make an engine run. You need to figure out which you don't have when it won't start. I'd start with spark and have a friend help you check for spark next time it wont start in the rain. Also, did you use Genuine cap & rotor or cheapie aftermarket? I have had multiple wierd running problems with Defenders using inferior ignition components.
 
#6 · (Edited)
Rob, I used genuine parts (I did it as part of a 100k service). Sounds like a good idea...the gf's going to have to get wet next time it rains! It's just frustrating because I can hose down the engine and it fires right up...but in the rain, when the engine itself is dry, it won't start. I'm also going to pull the dash apart to see if anything important is getting a little wet.

A few summers ago while driving cross country the Alpine alarm (installed by a previous owner) fried and I had to do some emergency wiring...it was under the dash on the left side. Nothing else seemed to be effected, but I'm going to check anyway. As far as I can remember this problem started about a year ago...so? Luckly we don't get much rain here.
Thanks for the ideas!
 
#7 ·
I would still check the coil. Mine is mounted with the point facing down and has the tendency to have the rubber boot fill with water and cause problems--that is until one frustrated day going through a puddle and I stalled at the rally and someone handed me a tube of silicone and I sealed it shut. Funny thing was that I always use silicone grease in such circumstances and they gave me silicone sealant...well, it won't fall off by accident, I will tell you that much! No problems since, and easy to diagnose.

When it won't start, pull off the high tension lead off the coil, spray with WD40, put back on a see what happens...
 
#8 ·
You may aslo check fuses.
When it rains hard I have some water that runs down the firewall to the fuses.
Do you hear the fuel pump cycle when you turn the key?
Do you smell gas if you continuely try starting?
When it does start does it run rich?

I had the same problem and it turned out to be a bad lead to the positive side of my coil.
Good Luck
 
#10 ·
Recently, the no start after being uncovered in the rain, started to happen. A few days ago I fell asleep before putting my truck in the garage. The rain came, and it was long and consistent. Next day, car wouldn't start. Crazy thing? It was under a pull up canopy that covered a majority of the truck. Having this happen before, I didn't panic. I first started noticing this happening sometimes after simply washing the truck. I just read through all the treads. Some dating back to 06. I didn't find a definitive answer as to why this is happening. I also discovered that this is not an isolated problem. Many owners have experienced this. But... there is one question that hasn't been asked, nor addressed. If the issue is a possible crack in the dist cap, the starter, fuel regulator, ecu, wire connectors, etc..... How/Why is water getting under a closed bonnet and traveling to all of those parts??? Especially when the truck is not in motion, closed vents, on level ground? Is the truck that vulnerable?? I mean, I would love to take a road trip up north and spend the night in a rainy, sleepy town. I also want to be able to leave that sleepy town! Has anyone out there found a definitive reason why this is happening?
 
#13 ·
Has anyone out there found a definitive reason why this is happening?
I could have this slightly wrong, but the humidity makes it harder for the electricity to stay on it's designed-in course. It's more able to just migrate out into the air rather than pass thru corroding connections, etc. Of course, you must always adhere to the troubleshooting procedures described in the service manual. Alternatively, how old are your spark wires? If older than 1 year, a generous helping of dielectric grease applied to the connectors on the plug ends might help.
 
#11 ·
For me the engine wasn't wet per say, just the moisture in the air during rain or heavy fog when it was parked outside for a while was enough to cause problems with the cold engine. Mine turned out to be the ignition amplifier. I looked at everything else then started messing around with it after reading a bit on here after that last post in 2006. When I doused it in WD40, truck started right up. I put a relocation kit on with a new amplifier not too long after and have never had any issues with it since.


I don't recall if it's the exact kit I used, or just similar (below), someone here offered/sold me a kit. If you do a quick search, there are any number of threads here on how to do it yourself without a kit. Or you could just replace the amplifier where it is, if that's your problem.

 
#14 ·
We had used the amplifier relocation kit linked above on Trey's 110. We mounted it next to the coil which was mounted just under the fender/hood gap. We had the same issue and found that spraying everything with a waterproofing silicone spray was a game changer on his truck. Grounding the amplifier is key and water running in between fender and hood was causing issues.
 
#25 ·
The ECU sits in a prone spot for water to run down inside and get to the main plug. Pull the plug off and peel the rubber boot back and look for "greening" on the pins. If so you can clean them and then pack it full of diod-grease. You can also open up the ECU and spray it out and then seal the rotted gasket and put it back together.
 
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