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'97 Jeep Wrangler won't start in damp weather

I have a 1997 Jeep Wrangler soft top that when it rains and the temperature is 45 or above I get water on the floor boards and it won;t start.

Once it drys out it is fine and it is also fine reagrdless of how cold it is. Any suggestions? We have had it to 2 mechanics with the oxygen sensor and distributer cap being replaced and still have the problem.

How does it not start? Does it crank but not start running? Does it not crank, but only “click”? Does nothing happen at all?

It turns over but does not start.

It could be many things, but how old are the spark plug wires? Then tend to get sensitive to damp weather as the age.

If that is not it, then I suggest buying new spark plug and carrying it with you. Next time it happens remove one spark plug cable from a spark plug and put the new plug on the cable, Hold the threads of the new plug tightly against the engine and have someone try to start the car. You should see a bright blue spark at the tip of the plug, if not you have identified a spark problem.

Note if you see stars when holding that spark plug against the engine block, that means you did not use a good insulated tool, but it also verifies you are getting spark to the engine (use a well insulated tool to hold the plug against the engine.

A question or two: Did the mechanic pull a code to find a need to replace an O2 sensor? If so, find out the code NUMBER (eg. PO123) and post it here.

When was the last service (‘tune up’) performed? What was done/replaced?

Changing the distributor cap is one possible cure, PROVIDING the original was getting damp inside from moisture.
Maybe he just took a long shot and hoped it would be the fault, but obviously not eh?

Soft top. Water leaks. Floorboards wet.

If excessive moisture is getting inside, perhaps some of that moisture is affecting the ignition system and causing electrical problems.

In that case I doubt that the water on the floor is causing the problem (I was thinking maybe the clutch interlock switch was getting wet). It most likely the old wet ignition problem. Your mechanic replaced the distributor cap. He should also have replaced the rotor. What about the wires? If they’re original, they’d need to be replaced by now anyway. Same with the spark plugs. Another possibility is a weak spark coil. Any chance you could leave it at your mechanic’s on a night it’s forecast to rain? That way they can test your Jeep under the failure conditions. Good luck and keep the rubber side down.

I’m not sure about the code and we have not had it in for a tune up in years. Other than replacing the stabilizer this is the only issue we have had.

Also, the radio stopped working if that means anything.