First of all you don't have a carb, you have fuel injection. My first guess your problem is a failing fuel metering valve or maybe even a failing fuel pump. Good luck
you should shut it off... Then you should wait a couple hours. Then you could start playing again.
It maybe the Thermostat if it bad the 4.3 will quit and not start untile it cools down
Take the blazer to a local autozone to have the battery tested for FREE! but the blazer would not start if it sat for a couple days or so. also it would start hard, but once it started it would run fine.
More than likely a low fuel pressure problem, or the fuel pump is gradually dying. it shouldn't have a car, rather TBI or a vortec setup. im thinking tbi, it looks like a carb, but has two big injectors over the intake holes.
It's condensation. The pipe dries out in use but gets very hot. When the pipe cools it draws in air from outside and any water from the air collects in the pipe; even in a couple of hours on a wintery day.
Drain the blazer radiator. Refill with water. Open the heat on high, start the engine for a few minutes. Drain the system again Repeat this several times to get all of the old coolant out.
possibly bad o2 sensors! Check ignition switch
this also happened to me and the first repair was the coil in the ignition had broke inside so there was just a bit of contact but no full connection.... now the problem is once i used the blazer for a while and try to start it up again in less than 2 hours it will not start...now I'm told it's the sensor for oil pan
Fuel filter could be clogged, try fuel injection cleaner if it runs better then it is a clogged fuel filter. Keep in mind you might have to pump the gas pedal to keep it running.
This takes a lot of patience, maybe something scared him/her the last time outside, so you may have to start all over again, it takes love, and patience ( every couple of hours to go back outside)
Blazer K5
1998 chevy blazer wont start good spark and good fuel presure