Well for starters, thats the last year for the CPFI or sometimes called CMPFI. Either way it really has only one injector with six poppet injectors. There are two common problems with those systems and they are NOT cheap to fix. I know, been there, done that. Those Vortec V6 engines are good motors and last a long time but what happens is the fuel rails that goes into the two piece intake manifold that goes in the back of it usually leak badly. Gas puddles up in them and sometimes they blow apart. Not trying to scare you just tell you the truth. The other part that goes bad is the Central Fuel Injector itself. Usually they leak from the fuel pressure regulator. Mine did and both leaked and gas puddled up but fortunately I fixed it before it blew. Its not too bad of a job to fix it. Just that the parts are outrageous! You don't have to drain the raditor to fix it. Just take the plenum or upper part of the manifold apart and you can replace the parts needed. If the rails have never been replaced, replace them. They squirt a fine mist of gas into the air and settles inside like I mentioned. Sometimes you can't see it do it. About $600 for the fuel rail and injector kit. I have a spare injector which I am not using if you are interested. You can only buy them from the dealer. You can try to get them elsewhere but I couldn't. The FI inside is easy to remove and just disconnect the plug and one screw then squeeze the poppet injector clips and they come out and looks like a spider. Make sure you snap the new on in place with new o rings and there you go.

Just curious what you found out for your problem. I have the same vehicle, and of course, the same exact problem. As it has become cold, the Blazer will not start. Sometimes I can finally get it started, and once I do it is fine. It starts up everytime after that until it cools down. The cold weather does that pretty quick. Then no start again. I will drain the battery numerous times and sometimes it will finally start. Othertimes it still will not, like now. Just won't start. I'd be interested to know what you had to do and how it went.

You checked the coolent temp sensor conductivity but is can still fail and show conductivity. I would suggest replacing it anyway. It is not an expensive part and very likely your problem.

I have been having that exact same problem. I did change the Temperature Sensor, but the problem still happenes. The funny thing is that when I changed it, the problem went away for about 12 days. Then, it came back. I wish I knew what was happeneing.

On 4.3 W CPI Possible internal fuel leak, check fuel pressure specs. Fuel regulator leak can be inspected by removing valve on top of plenum and looking for fuel leak in plenum when key is cycled to on. Also check wiring harness to CPI injectors