Kia Troubleshooting Questions? Ask a Mechanic
What you describe sounds like either a weak fuel pump or bad spark plugs. Next time you go to start it up can you try the following:
Turn the key to the run position for 3 seconds then back to off, then to run for 3 seconds, then back off, then run for 3 seconds, then back off, and then start it. This will prime up the fuel pump. If the engine starts right away by doing this then you know that the fuel pump is the problem. If it doesn't make a difference then the problem could be bad spark plugs. How old are the plugs?
Weak fuel pumps are affected by temperature also. Sometimes they work better when cold, sometimes better when it's hot. Then sometimes it works fine for a few days with no explanation. I would definitely suspect a dying fuel pump. They really aren't too terribly hard to change on the kia.
Please let me know if you need additional info.
That's probably helping it along. Warm fuel pumps easier.