Having trouble with a MIS-leading gas gauge?

Hello there,
I have been having trouble with my gas gauge when i first bought my 2000 Bravada 6 months ago. The gas gauge will say FULL even if the gas tank is almost empty and it would jump back and fourth btwn EMPTY and FULL, leaving me stranded once without gas.

Now the gas problem escalated to the fuel tank, when ever i pump gas into the fuel tank at the gas station, the gas station will stop pumping gas into my fuel tank, as if it were full, but it would pump gas if i was carefull at lightly hold the pump and not let the gas pump too fast.

I have search the Blazer forum and think that just changing the sending unit on the gas pump will solve this problem, i really can't afford a new gas pump.

Sorry for the long and confuzing but this is not the first time the folks at this forum bail me out.

P.S Do you reccomend me taking a 500 mile trip with this problem.

Sending unit needs replacing.

Your vent on your tank is blocked closed.