2000 Hyundai Tiburon car sometimes won't start

I can't be sure without a few checks of it is the fuel pump. I assure you the pump isn't stopping the fuel from entering the tank.

First, when the car won't start, check you need to check for spark and fuel to the engine. One will most likely be missing. Here are the how to steps for checking both.

https://www.2carpros.com/how_to/how_to_test_an_ignition_system.htm

https://www.2carpros.com/dia/test_fuel_pressure.htm

If you find there is no fuel, open the fuel cap to see if there is a change in fuel pressure.

Next, the problem with filling the tank can be one of two things. First, there is a check ball at the end of the filler tube where it enters the tank. Its purpose is to prevent fuel from leaking in the event of a rollover. It could be sticking, thus preventing fuel from entering the tank. Also, if you ever noticed, there is a breather tube next to the filler tube that can be plugged. One of its purposes is to allow air to exit the fuel tank when being refilled. If it is blocked, the tank remains full of air and the fuel has nowhere to go.

Let me know what you find on the no start situation so I can further direct you on that issue.

Joe