98 s10 wont start after a rain

I have a 88 s10 with 92000 miles. It is a very basic pickup with no frills. It has 2.5 and a distributor and efi. I live in Utah, a very dry state with very dry air.
The day after it rains, it wont start. I don't even have to drive it the day it rains. If fact, it only has to be a moist night with a lot of dew and cool temps. and I can't start it the next morning. I about run the battery down trying. Usually after 10 minutes of trying I get a few puts from the engine and then after a few more tries, it will start. I have had to pull it a few times to get it started because it just wouldn't start. Once running, it runs great and will start right up every time until it sits all night and it is a moist night. If it is parked in the garage, it starts every time. Too bad the garage doesn't hold all the vehicles!
What I mean by won't start is the engine turns over just fine but the cylinders won't fire.
I checked the firing of one of the spark plugs and it has no spark or very weak spark at best. I'm thinking that moister is getting into the distributor some how. The oil looks good so I don't think it is coming from the crank case.
Any one shed some light on this problem?

I have a 88 s10 with 92000 miles. It is a very basic pickup with no frills. It has 2.5 and a distributor and efi. I live in Utah, a very dry state with very dry air.
The day after it rains, it wont start. I don't even have to drive it the day it rains. If fact, it only has to be a moist night with a lot of dew and cool temps. and I can't start it the next morning. I about run the battery down trying. Usually after 10 minutes of trying I get a few puts from the engine and then after a few more tries, it will start. I have had to pull it a few times to get it started because it just wouldn't start. Once running, it runs great and will start right up every time until it sits all night and it is a moist night. If it is parked in the garage, it starts every time. Too bad the garage doesn't hold all the vehicles!
What I mean by won't start is the engine turns over just fine but the cylinders won't fire.
I checked the firing of one of the spark plugs and it has no spark or very weak spark at best. I'm thinking that moister is getting into the distributor some how. The oil looks good so I don't think it is coming from the crank case.
Any one shed some light on this problem?

That is usually cused by a bad dist cap.
Hair line cracks!!!
That you sometimes cannot even see.
Pull cap when no start and look for moisture inside.

I would replace cap and rotor and plug and coil wires to.

Thanks for your post MT-2500. The Pickup was having a hard time starting today and I stopped trying to start it so I could check for moisture as you indicated. I wanted to find out just what the problem is, so I have decided to change one component at a time. Realizing that just moving the other components might correct a problem inadvertently.
I set out to change out the distributor cap first. In so doing, I rubbed the heater water line directly above it were it comes out of the water jacket of the engine. I felt a little drop of water. Looked at it with a mirror and could tell that a very very very small leak was making it moist in that area, the bottom side of the threads going into the water jacket. It just happens to be directly above the coil wire on the distributor cap. Looking into the coil wire I could see it was corroded and had the slightest bit of moisture on it. A drop must have formed and dripped on it earlier in the night because it defiantly wasn't wet now.
The cap was in great shape. Almost no deposits but a little dirty on the outside. The rotor looked almost new. No sign of wear at all, no deposits, and no sign of arcing.
I have cleaned up the coil wire connection, added boot sealant/lubricant and will work on the heater water hose leak today.
If I still have trouble, I will start replacing all the items you mentioned. (it's going to rain this weekend)!
Thanks for taking the time to point me in the right direction.
RCWeston

You are welcome.
And thanks for posting back what you found and how it is going.
It sounds like you found your problem area.
Get that leak fixed for sure and on the coil wire and plug wires they make a spray on stuff for sealing them from moisture

It's has been a couple week now since the repair and it finally rained, three days straight, time to put the repair to a test. It stared right off the bat within 1 or 2 seconds, the first morning after the rain, the next morning it had a 4 or 5 second hesitation, and today it started again with about the same 4 or 5 second hesitation. That's much better than cranking it for up to 10 min as it was before! Time to replace all the old items mentioned with new ones. And I got a good hint in the blazer post section, that is to seal the bottom of the distributor cap with a little grease to keep out any moister if something doesn't fit tightly.
thanks again everyone. I'm sure an other problem will pop up again with a truck this old. Until then, thanks
Rex

It's has been a couple week now since the repair and it finally rained, three days straight, time to put the repair to a test. It stared right off the bat within 1 or 2 seconds, the first morning after the rain, the next morning it had a 4 or 5 second hesitation, and today it started again with about the same 4 or 5 second hesitation. That's much better than cranking it for up to 10 min as it was before! Time to replace all the old items mentioned with new ones. And I got a good hint in the blazer post section, that is to seal the bottom of the distributor cap with a little grease to keep out any moister if something doesn't fit tightly.
thanks again everyone. I'm sure an other problem will pop up again with a truck this old. Until then, thanks
Rex

if it does it again after you get it started let it cool off a little put wire dry on all plug wires and coilpack i had to do it in my 91 and it works my ford ragers have same problem back in early 90's even with seperate coil and dist. they had to be sprayed with wire dry. they say w-d40 is same it's not you'll smell it longer to.

On a slow start cold always check tht fuel pressure for up to par on the cold sart.
Also try key on and off and on a couple of time to let the fuel pressure build up.
Good Luck

Thanks everyone for you hints and helps. I'm Happy with the starting problem. It seems to start within about 1-2 seconds every morning now. What a difference such a little problem can be!
Rex