HELLO ALL, second post. Two months ago purchased a 1996 4 dr blazer w/4.3 with 77k. Truck runs great except when it has rained or is raining. Truck hesitates and is sluggish, servive vehicle light comes on also. Have some mechanical experience, so probably electrical, the wires? If I replace should I also go whole 9 yards and due complete tuneup (at mechanics). Appreciate all replies. Thanks

 

My blazer has the same problem when 1 hit puddles. Its an exposed wire somwhere... I don't know where.

 

It is also quite possible you have a cracked distributor cap. If moisture is present in the cap, it will cause the spark to scatter instead of being directed into the wire, causing the misfire/stumble you are experiencing. A good tune up consisting of plugs, wires, cap & rotor should be done if you don't have records of when it was last done... Faulty plug wires can leak spark as well. If you want to check the wires, go outside when its dark. Fill an old, thuroughly cleaned out spray bottle with tap water, and mist it over the engine, specifically trying to wet down the wires and their surroundings. If you see sparks jump, you know what you have to do.

 

I work on atvs almost every day and a known problem concerning your situation would be a cracked intake tube or an excessive amount of moisture getting in the air box.

 

Check the coil wire. That was my problem.