What is wrong with my grill?!

Best Answer - Chosen by Voters

You wouldn't have this problem if you used charcoal, but that's another story.
Old white sounds nuts, but he might be onto something. There could be a clogged line or your burners are clogged. They may look fine but might have rust or food particles/grease clogging the holes. You might need to unclog the holes with an opened paperclip.
Are you 100% sure that your tank is full of gas? It could have leaked out slowly over the winter.
I have only owned 1 gas grill, but changed the burners twice, replaced the igniter and decided to go back to charcoal for the flavor and ease of use.

You're not going to believe this, but I fixed mine after talking to a repairman. There is a microscopic spider that loves the smell of natural gas. They climb into the orfice and make a dense little web there. I took my grill down to the point where I could unscrew the brass orfice and there was something that looked like a loose cotton ball. Trouble is, it happens every year in Southern California.

There is another cause which also happened to me. The pressure regulator which is attached to the tank just stopped working. Went to Home Depot and bought another one, and it works. Change the regulator first, maybe $12.