Son called said the S10 is not starting when wet/raining. Just turning over. About 4 years ago I replaced the distributor cap, wires, and spark plugs. Also replaced the ignition switch and installed a Delphi revised fuel pump.

Any thoughts on what may be the problem. Note I used all OEM ignition parts. One thing I am thinking is the fuel pump ground wire may have some corrosion; maybe when wet it may be enough to disrupt continuity.

S10 is 800 miles away- I am unable to visually inspect/ troubleshoot.

Spray WD-40 inside the dizzy cap, shake out the excess. Cheap caps let moisture in. No-no for dizzy caps.

Next, try a new wireset. Rjblazers truck did the same thing a few weeks ago. We seen the primary ignition wire arcing and I swapped mine in, fired right up.

My wifes Blazer would run real rough if the outside humidity was high(ie rain) until the engine warmed up. There is just something about these engines with the dizzy'* unlike our little 3800 with DIS.

On another note, me thinks 4 years is a tad long for ignition parts.

While inspecting the distributor rotor, check the vents at the bottom for cob webs or any abstructions that wont allow moisture to escape.

Dizzy'* have vents?

Does if backfire and pop? Or just crank with no start? I would check the ground at the fuel pump. I know it'* hard with the thing so far away but it would be nice to have a scanner on it to see if it'* registering RPMs while cranking.

Fathers *-10 had the problem missfiring only on wet damp mornings. Numerous caps and rotors installed, finally Found the vent hole below the ignition rotor on the distributor plugged with crap.

if it sits while he is at school, no cap and rotor vehicle likes that. you can get some fine sand paper and clean off the terminals and rotor and see if it improves. if not take a mist bottle and spray the wires while its running and listen for the engine to change, shen it does thats the bad part

Thanks for all the comments- forum has been spot on.

I thought a OEM distributor cap and rotor would last 50k+ miles and 8+ years. I was wrong, pulled the cap and rotor yesterday and plenty of corrosion, oxidation, and overall wear. I am guessing the cap and rotor were replaced around February 2011.

Replaced with new OEM cap and rotor. Plug wires and plugs soon to follow.

Keep us updated!