So my 02 Blazer has been having this problem for a couple of summers now (it only happens when it gets hot e.g. summer...), but last year it was supposedly fixed. It will be running fine and all of the sudden it will start to sputter, my RPMs will become inconsistent and it will die. It will start again but will immediately act up unless I take the gas cap off for a few seconds before starting it up. Even when I do this it will die again a few miles later. Any ideas guys?

 

I think this is due to pressure build-up in the fuel tank. There is a solenoid / valve that is supposed to relieve this pressure...the purge valve or I might be thinking of another vehicle. If you look at the emissions label it should show this.

So the problem could be a relay, or a leaking vacuum line that is keeping the system from bleeding the pressure.

Should be an easy fix.

Keep the thread updated with any findings....as I have an '02 and am a bit interested in this.

 

yup, in the old days Gas caps had Vents.

But now the Emmissions police have added two electro mechanical failure points to the cars so the gas doesn't vent out to the air.
I would guess you are getting a Code. P0440 /P0442maybe?
There is a solenoid On the engine , passenger side with a hard hose coming off it and a solenoid on the crossmember , in front of the spare tire. I bet one of these is not opening to vent the gas tank into the intake manifold

 

Alright sorry it took so long, but it turns out that removing the gas cap is not actually helping at all. There is nothing audible when I do remove it so I don't think that there is pressure build up. The real problem is that it isn't throwing any codes at all (no CEL either) . I took it to the shop and they told me that they can't find anything wrong with it, through their regular diagnostics (whatever that may be), and an evap test, and nothing. It was fine for about a week but then it died on me while I was coming home from work and I had to have it towed home. I think the alternator might have something to do with it, I just replaced it about two months ago with a refurb from autozone but my dash lights are dimming again and I can hear it whining while on the gas.

 

That is similar to how my 2000 S-10 behaved when the fuel pump was beginning to fail.

 

That makes sense, JWhis, if the alternator was dead it wouldn't even crank over right?

 

You need to do a pressure & leak down test on your fuel system.
If you put a volt meter across the battery terminals with the truck running it will give you the voltage. 13.2-14.2V is normal. A good battery with engine off you should get a reading of around 12.5v if everything is working correct.

 

So it turns out that the throttle body plate was not adjusted correctly so it wasn't closing all the way at an idle. Cleaned the tb adjusted it, and that helped, however, I have been skeptical about the alternator so I took it out and while I was doing that I noticed that the extended post from my battery (side posts so needed when I did the stereo a while back) wasn't tightening all the way. Took the alternator down had it tested and it failed... 3 TIMES! Made them replace it, tested the new one a handful of times, bought some new battery posts and off I went. Put the new alternator in, replaced the posts and she hasn't died on me yet. Is there a length of time that it takes the computer to realize that there is a new part in it? The reason why I ask is because I still get a quick flicker when I turn my blinker on.