Topic: Wet weather, big problem

[TexWalther]

Hi all, am trying to find a solution for a problem that I have been having over a year now. 90% of the time my jeep starts right up and runs like an underpowered champ.. However, on days when it is wet outside, much rain night before or just a summer morning when condensation covers everything I almost can't get her to start and when she does it runs extremely rough until the motor has warmed up, often dying on me.. have looked for arcing and cant see it happening anywhere. have also changed plug wires and distributor cap.. Am almost certain this has to be an electrical issue, however i can't find its cause.. any suggestions?

[YJmechanic]

Could be several things but start with this, change The rotor, put a little sealer around the base of the the distributor cap to keep moisture out, and then check and make sure the coil doesn't have a hairline crack in it anywhere, that's where is start

[sharpxmen]

also, put dielectric grease around all the contacts, that should help keep the moisture out. sounds like a bad wire and running in 3 cylinders, i would try to remove the wires off the plugs one at a time and see which one is not contributing, careful as you get shocked easily when doing this, thick gloves could help but not guaranteed

[Jeffy]

I'd start with dielectric grease and reseating the plugs.  TPS, CPS, PCM, etc...  You might try covering individual parts with a plastic bag to see if that helps.  You might be able to isolate the issue to one area that way.

[aw12345]

Why not stop and spray the cap, rotor and wires with wd40 if that resolves it, you know what you need to change.

[TexWalther]

Alright guys, know this is an old post, but as the problem is intermittent, it is very hard to stay on top off. Since this post i have changed the igntion coil, and another new set of plug wires. I have in the past year changed the CPS, TPS, fuel pump (know that's irrelevant) yet i still cannot start my jeep on wet days... Know i have already asked this question, but does anybody have any new suggestions???

[neale_rs]

Try removing the coil wire connectors and spaying them with WD40 next time it won't start.  If that doesn't work, try spaying the cap and rotor next.    You could also try spraying the relays to see it that is the cause.  Do one thing at a time to try to identify what is happening. Also, try to think about what might  be getting wet either by dripping water or by condensation.

[TexWalther]

just sprayed the plugs, plug wires and underneath the plug wire caps on both ends. Sprayed the ignition coil, took the distributor cap off and sprayed everything under it... guess the relays are next..
      

[sharpxmen]

did you check if there's spark at the plugs when this happens? should be the first step to troubleshoot (use another plug and crank it), if there's no spark then move to the ASD relay and check for voltage output when cranking it (you can test at the coil connector, one of the wires comes from the ASD), if there's no fuel check the Fuel Pump Relay, if they're both good check the connection at the crank and cam sensors (although if you get voltage out of those 2 relays it means you get crank signal), if all that is good then it's the PCM :-(

[neale_rs]

If the check engine light does not come on right away when you turn the key to run (assuming the bulb is not burnt out), it's almost certain it's the PCM.  Went through that a few years ago, and wet weather did tend to make a difference.  Sometimes I would leave the key in the run position and after a while the PCM would light up the check engine light and activate the fuel pump so the YJ could be started. But as long as the PCM did not activate the pump, no start.  The problem got worse as time went on until it could not be started no matter how long I waited.

[TexWalther]

Check engine light does come on when i turn the key. I am getting spark, can tell this because it will start very briefly. It is pumping fuel... unfortunately i dont have a voltometer so i dont have any way to check my voltage... Sprayed the relays down, still nothing.. unfortunately it is starting to get sunny out so im worried everything will once again dry up before i can find the problem

[sharpxmen]

you can get a multimeter for under $10 at an autoparts store or harborfreight. Spraying the relays does almost nothing, it's the contacts inside that usually go and not the external terminals.

if it starts briefly can be that you get voltage on crank and not run key positions, you'll need to have someone crank it and keep an eye on the volts, probably better in this case to use a check light rather than the voltmeter.

it can also mean that you're running out of fuel pressure (so it could make pressure when you switch the ignition on and then the pumps stops), and the more weird scenario when your injectors are cut out due to lack of cam sensor signal.

You'll have to troubleshoot all this more thoroughly as unless you get lucky and guess exactly what's happening it could be a constant hit and miss.

[neale_rs]

Maybe something wrong with the ignition switch down on the steering column in the RUN position.

[TexWalther]

Ignition switch has been mentioned by someone else also. Had a problem with it starting on a dry day, they messed with it and seemed to think that was the cause... Was the 1st time its ever acted up on a dry day so i kinda ignored it... Seems seperate of my usual problem that im having today, definitely something to look at though... guess i will run to the store when a roommate gets home and pick up a multimeter..

[TexWalther]

Ignition coil i bought last week was cracked, didnt see that until i had someone else cranking it. Seems to be fixed finally, reckon we will see next time it rains though..