I have a 97 tj and it never wants to start after a night of rain..If I need to start it in the morning, it will take anywhere from 15 minutes to a half hour to start, and even then it will sputter and shake for a few more seconds before running normally. The plugs are fine and there is no moisture in the distributor cap. Any one else have this problem, or any ideas how it fix it?

You have several sensors that can get fouled up with time and they
can get sensitive to water. The obvious stuff is to check the ignition
side - but the idle sensor, temp sensor, and the MAP sensor can have
problems because of water.

Never Never wash your engine without covering these sensors because some
makes will just die from a wash - cover them with plastic - and avoid
direct spray on them.

Unless you have some specific idea what might be wrong you have to go through
a set of cold start tests. With a 97 you might have to go start with compression - it might be cold and wet ...

Plugs, wires, cap, rotor - check for damage - cracks - worn contacts - bad
wires - fouled plugs. Check to see if your timing is correct.

Once you have it running clean the intake with carb cleaner, you are looking for black fouling - clean it off because it blocks the sensors
in the intake tube. If you have never done a compression test it might
be good to get a baseline - and record it in your maintenance log book.

Check the wiring on your sensors and clean the inside tips only with cleaner - never submerg any sensor - just clean the exposed parts - the
tip that goes in the engine - use new sensor safe sealer when inserting
clean the contact surface of the wiring in/out and put some contact greese on it. Checking each sensor is hard but you can find the text on the
net - by the time you get here you should have an idea what is wrong.

If you have not done a tune up in a long time you might as well do the
tune up run - plugs, wires, cap, rotor, air filter, etc. when you do this.
since this is a manpower thing and it takes almost as much time to check
these things as it does to replace them.

Get high quality parts - not the cheap stuff - check the gap on the
plugs going in and record the state of the plugs coming out - color and gap
so you have an idea what the state of the system ... Clean the plug wholes with brake cleaner and use air to blow out any dirt in the plug holes. Get good wires and be sure to use contact greese on them cap and plug.

If you are new to this and do not know the basic tricks - does and don't
find someone who is to help.

The basic problem is to check the ignition - with the timing being the last
item - check the intake with the sensors - check the fuel flow - then the compression.

Be careful with any connector - they all have clips to hold them in so if
you don't disconnect them correctly they will break - and add to your problem. If you have a digital camera do a once - twice picture run of the
setup before you start taking things out - so you don't forget...

If you are going to keep the rig consider getting the Jeep Factory manual for $120 - it has the diagnostic procedures for all this stuff in it - it
may specify special tools but you can work around this.

When I said clean the plug holes - I mean take the wire off - leaving the old
plug in - spray with cleaner and blow dry - never blow or spray into a plug
hole that does not have a seated plug in it. Tricks ...

Twist your plug wire gently when you remove them - do not yank on the wire.
More damage is done to wires - just checking them because people crack the
wire - and damage it - it looks OK but causes intermittent problems - like you
no start during rain ... Use electrical ignition contact grease on both ends so the wire end does not corrode or get water in it. Do one wire at a time so you do
not get the wire runs wrong. Pictures are nice.

Alternately to AZJeepers very good suggestions, you can also clean out the garage, and use it to keep your vehicle in

Anyway, I don't understand how a rain will affect a jeep - do you have any unusual mods ? Do you leave it out with the top off, the hood off ?

in my opinion i doubt it could be from leaving the top off in the rain because i leave my top off from the end of may till the first day in fall that i need the heater. The one thing that i would check is ur starter, i used to have problems with my starter when i would go through alot of water. it would run ok but as soon as i shut off my jeep it wouldn't start for a few hours sometimes even a few days. i am now on the 3rd starter since i bought my jeep 4 years ago and it hasnt happened since. try the wiring first make sure it has a good connection and then put on some of that grease AZ was talkin about. i found sometimes that if i wiggled the wires while a friends started it then it would sometimes work. good luck

What I said assumes alot - I am assuming that you
are getting a cold start - vs - no start.

A cold start means you have the starter engaged
and it is turning the engine over - but you have
a failure to start the engine - floods out - or
not start - backfire - etc.

If you are getting no crank - or a poor crank - you might be looking at a starter , wiring, or a battery problem.

I'd check the voltage on the battery any time I think that might be bad - you are looking for
12.6 volts or close cold - anything below is
a warning - 13 plus running.

I replaced the starter once in 85K on my 98 so that might not be a bad thing to check. Mine no started just twice before it was gone so who knows. Although you would think we don't have much water here we get water problems in the mountains.