I can't get gas in my gas tank. No matter how I hold the nozzle the pump automatically cuts off after just a few seconds.

A bad gas cap will cause the light to come on, of so replace the cap. The vent is not working if gas is coming back at you. Replace with new.

Gas pump nozzles have a device in the end that when gasoline runs back up into it, it turns off the fuel flow." There's a tiny hole near the bottom of the gas pump nozzle connected to a small tube.
Normally, air flows through that tube while you're filling and the gas keeps flowing as long as you hold down on the trigger. When that hole gets covered by gasoline (when your tank is full), a vacuum forms inside the nozzle and an automatic shutoff switch gets tripped, turning off the flow of gas with a thunk. Next time your fueling up try to reposition the nozzle.

check that the air hose from the tank to the top of the filler pipe is not squashed or crimped by something like a zip tie. This hose allows the air in the tank that is being displaced by incoming fuel to vent at the top of the filler tube and not past the filler nozzle thereby switching it off.

When taking gas cap off give it a few seconds for the pressure to escape from the tank. Also you may not be putting the nozzle in far enough for the fume preventor(the rubber thing on the nozzle)to press down. That will make it stop pumping gas. Sometimes you have to press the rubber down when it is cold out.

You should have a check light on the dash,no??

You have an EVAP System Malfunction,such as a
fuel tank vent valve failure etc

Need it diagnosed and repaired

It is the angle and restricter in the fill tube plus the pressure from the pump causing it to do that. There is nothing wrong with this. You need to find the best angle to use when filling the vehicle. I had this same problem in a 2005 Escape. Had had to find the right place to hold the filling handle and the right position to hold the grip to get it to stop.

Same problem yesterday on my Dad's Jimmy. Left my brother in law stranded cause they couldn't put gas in it. There is a pressure purge valve next to the tank that is supposed to release the pressure on the tank when the engine is shut down. These often fail in Jimmy's and Blazer's and because the tank is still pressurized, the antisiphon valve doesn't open up and this keeps you from putting gas in the tank. You need to replace the part.

I am having the same problem. When turning the pump on full speed it will pump for a few seconds before kicking the pump off like the tank is full even though there is no gas in the tank. I can pump gas if I barely start the pump and hold it by hand but very very slowly so it takes about 20 minutes to fill up. Its not the gas station or the way I am holding the nozzle as I have stopped 20 different places and tried every way imaginable to hold the nozzle. I have changed the filler neck, charcoal canister, and the sensor/filter that is on the side of it that I believe opens to allow fuel vapor to escape and let pressure off the tank when the truck is not running... still no luck. When I had the fuel next off there is a check valve that is made into the top next part of the tank that is spring loaded. I figured this was to keep gas from running back out in the event of a rollover and possibly keep someone from putting a hose down the next and stealing gas. At this point that is the only thing that could possibly be causing the pump to contiune to kick off every few seconds when filling up the tank. Next is to change the tank I suppose unless someone has already ran into this issue and can tell me what I need to do to fix the problem.

I have had this problem. For me it's usually when the tank is really empty. I worked at a gas station and at times, I'd have to replace the gas nozzles when they wouldn't kick off correctly.. I suspect the problem is that the gas nozzle is picking up more gasoline fumes that are being displaced in the tank and venting thru the fuel filler opening. The gas nozzle detects enough gasoline vapors with it's sensor to shut-off the nozzle. One can slightly adjust the nozzle in the fuel filler opening (or wait a few additional seconds giving time for the fuel vapors to exit the fuel tank)) and it works great.. I do not believe it is a problem with the Blazer. It's a combination of the gas nozzle and the amount of vapor escaping the filler opening with the displacement of vapor in the gas tank. I've had this happen in my Ford Contour.
I hope this helps others.

The fule tank vent tube is blocked/clogged. It's the little hole next to the filler hose that invites spiders that clog it up. Blow out the tube and it fixes the problem.