I have a 1999 Blazer with 212,000 miles on it. I have treated it royally and besides basic maintenance I have only had to put in two new fuel pumps. It seems to run great in the normal clear weather but on a rainy day it will start up and misfire like crazy. After driving it a while stopping places and restarting through the day to drive it, it seems to correct itself. I have fine fuel pressure, new cap, rotor, plugs, wires, map sensor, 02 sensors are fairly new. What might be making this happen in moist weather?

 

does your filter stay dry? it might choke a bit if you're sucking in some water.

 

sounds like damp ignition parts

mine does the exact same thing i had trouble getting it started today wet weather and damp out all crank no fire.

took the dist cap off and dried it out along with the rotor .

then i soaked the cap and rotor with wd-40 put it back together hit the key and it started right up

 

X2 change cap and wires

 

My guess, if they still have the vehicle, is that it's fixed by now. The thread is 6.5 years old. Please check the date before digging up an old bone

 

Oh way to "rain" on the parade Captain!

(I'm here all week folks!)