5v not working

Hello! I am building a line following robot for my club at school. I am quite the newb at this arduino stuff. But I need the 5v to power my robot. Every time i connect to the pin my arduino shuts off. I understand this is not safe for the uno, so i have stopped. I followed this guide: http://www.instructables.com/id/Line-following-Robot-with-Arduino/?ALLSTEPS The instruction say nothing about him having a certain setup as to his 5v needing to regulating.

Powering it all from 1 pin? Which pin?

If it's the 5v / usb pin then you're going to need an external power supply.

I left my battery pack at school so i am using my usb as a power supply, Which the output would be 5v, Right? Also i have my 5v working now but i can't have the ground plugged in with it. Is that okay?

Power supplies supply volts and amps.

Your "5V" is working fine but it can't supply enough amps, it shuts down when you overload it.

Then why does it work when I do not have a ground plugged in?

praleson: Then why does it work when I do not have a ground plugged in?

It doesn't, you only think it does.

The current will be taking a weird path through the components. If you do it too much then something will probably catch fire and/or die.

praleson: I need ...5v to power my robot.

Actually, in the crappy Instructable you link to I see a 6v battery pack to power both the controller and the motors.

You don't want to power the motors from the Arduino, but you can power both the controller and the motors separately from the same source. The 6v can come in through the Arduino's on board voltage regulator and supply the 5v for controller operation.