I mostly lurk here at Pirate...and I love it..tons of good info, of course I cannot see half of the pics...stupid working for a livin'! :mad3:

Anyways, I hope y'all can help me.

1995 GMC Sierra 1/2 Ton - 4x4 - 350 auto

It seems to me that on days that are wet the truck will stumble when under power in higher gears...It will idle fine all day long, in park I can gun it and no issues...but, going up a hill on the highway it starts missing..I mentioned wetness as the first sign i seen of this was the day after a big melting of snow here...i went through i deep puddle and sprayed water everywhere, the next day coming to work the symptons appear. Now, each time it happens it is wet roads...but, now i am sort of leaning to mild temps and possibly condensation or something somewhere because when salt is on road it makes slush right? - the slush does not seem to bother the truck....thoughts????

Moisture in the distributor cap maybe?

If you haven't done it recently now is a good time for plugs wires and cap/rotor. Most likely that will fix your problem... another possibility is a plugged or wet air cleaner...

Take your distributor off and spray inside the cap with WD40 and put it back on. You might wanna check to see if it is cracked also (sounds like it). Check your air filter might be soaked if so change it. let us know what happens....:smokin:

yeah, i will let you know forsure what happens. I was out at lunch, pulls and does not miss at all around town...funny it is only on highway, and usually up hills no?

sounds like a cracked cap

guys, distributor looks good..seems now it is not only a wet weather issue, or is it? - i am so confused, could it be coil, air filter, why is it only on hills at highway speeds?

i have also heard lots of stories about possibly being a coil issue...how could I prove or eliminate the coil?


Thanks guy,
B

I had a miss with my '94 Blazer 5.7L on wet days.....bad coil. It would ground out when wet and ran like crap. You could check it by misting it with water while running....see if stubles and runs poorly...my coil did.

As far as a stumble/miss at highway speeds could be fuel filter/low press. BUT it also could be a bad plug wire (or more) Mine was doing that recently, I had opened the hood on a dark night and i could see where my spark energy was going.....it wasn't to the plugs. I had three bad wires (small cracks in the unsulation) and the spark was grounding on other items under the hood. I suggest a full tune up 1st.....plugs, wires, cap/rotor.....oh and change the fuel filter if you haven't done so already.

CJ8, concerning the plug wires, while this was happening would your truck run fine at idle?

Yes, and completely fine around town (stop and go)...as far as I could tell. It did not manifest until highway speeds....and usually only under load such as pulling a slight grade.

Have you done the basics? <<< tuneup?

CJ8, i think you may have nailed it..my exact symptoms. I will let you know tomorrow.

Thanks for all the help guys and gals if any.

I would tend to agree that you are going to fix your concern with a good full tune up. Cap, Rotor, plugs, and wires. Especially check for a corroded terminal at the cap, if it is corroded up, just replace the coil as well.

Possibilities are carbon tracked spark plugs and boots/wire. Cracked/carbon tracked cap, and possibly a coil.

So if you haven't done a tune up lately, do that first. Also, make sure you get some silicon grease for all the spark plug wire boots.

The welfare mentality that is taking over this site is incredible. If your truck runs rough, do a tune up!!! If it still runs rough, then ask your question. But no, we just wanna be spoon fed...

FB, just be nice bro...:mr-t:

also, i prefer to be breast fed. Got milk? ; )

As info, plug wires were my issue...one thing i should have mentioned earlier was my task was very loopy also during this, makes perfect sense now. When I first started it sounded not very good and was burping like an ole pig. I had 2 and 4 backwards...I want to thank everyone for there advice and comments.

B