Auto Machanic Question

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Why won't a 98 Chevy pickup (5.7 motor) start after it rains? Has to be a hard rain and quick change in humidity. Gets no spark until it drys out. Ideas?

And no I'm not buying a new one or a Ford, Dodge, Toyota:thumb:.
 
Steve have you still got a rotor and rotor cup on that vehicle. If so check the rubber seals on the wires leading in and out of the rotor. I know if moisture gets in there on any motor it prevents the spark from getting to the spark plugs. I would do the same across the wires to the plugs too. Moisture is shorting the spark to ground somewhere thats my guess.

Warning i aint no mechanic. Just a backyard guy that has worked on some cars in my time.
 
Steve have you still got a rotor and rotor cup on that vehicle. If so check the rubber seals on the wires leading in and out of the rotor. I know if moisture gets in there on any motor it prevents the spark from getting to the spark plugs. I would do the same across the wires to the plugs too. Moisture is shorting the spark to ground somewhere thats my guess.

Warning i aint no mechanic. Just a backyard guy that has worked on some cars in my time.

BINGO!!! If no distributor, even older engines with an electronic module may have still have a distributor, it could be the electronic module is not sealed and getting moisture in it. My bet is still the distributor. Jim.
 
Yep still has cap and rotor. I have went as far as changing out the distributor. Helped for awhile, but now it is back. I pulled the distributor cap, before I posted this, dry as could be. Tomorrow I will put a used cap and rotor on and see what happens. What ever it is, has to be simple. Thanks for the ideas so far. Keep them coming.
 
WD-40, WD stands for Water Displacement and it will not interfear with the ignition. It was developed for use in aircraft to displace the water in the older airplanes when they had a problem with condensation.
The 40 is for the 40th formulation which is what it took to get one that worked.
Spray it into the distributor and you should be good to go.
 
Back in the '70's to get a car started to drive to the station versus laying on your back hooking to the wrecker using the J hooks, dad would pop the cap and turn it upside down, light a book of matches on fire inside of it. Many times this was enough heat to dry the inside of the cap so we could get it to the station and work on it in the warm.
 
Even with a good cap and rotor you can get arcing from any of the plug wires when they get old. I had the same problem on my old Dodge truck. Replaced the wires and cured the problem. Wait until night and see if you can see arcing when the engine is turning over.
 
New wire, a good set. Installed last year along with plugs. Changed to the old cap and rotor and fired right up. I have checked everything, still no luck. Only thing I am noticing is a lot of carbon build up on rotor. Guessing that gets damp and causes the short. Live and learn.
 
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