Continous supply of 12volt with relay

Please help as soon as you can, this is for a competition

Im trying to supply 12 volts a air pumper for 40+ seconds. Below is my schematic, however, after 10-15 seconds of the relay being turned on and the pump being supplied by the 12 volts, the ground wire start to melt.

How do i fix this? Thanks lot

If you want answers you have to provide full information on your hardware. "air pumper" could frankly be anything. Datasheet, part number, all the details you have. Just saying "12V" isn't enough!

The anti-spam prevents your first post from including images BTW, try again with that.

Melting wire suggests too much current so we need to know everything about your power supply, pump model and how it is all connected.

Draw a circuit on a sheet of paper and take a clear photo to attach to a post.