We have done everything we can think of. We've had the diagnostic check run & no codes are showing up. The only thing the manual says is that it's an emmisions problem. The gas cap is tight. Any ideas?

You might want to check the gasket where the fuel pump goes into the fuel tank. It could be dry-rotted. Or one of the hoses there (there are 2 or three rubber hoses in that area) could have a small crack or hole in it. You get access to your fuel pump by laying the back seats forward and then lifting the little square piece of carpet up. Remove those screws and take off the panel. Then you will see the hoses and wires to the fuel pump. Before you remove those screws around the fuel pump gasket... disconnect your battery. However, I will tell you now that Kia does not sell just a gasket, you have to buy the whole fuel pump system which (for the 2000 Sportage) is over $300. If you do chose to remove the screws that hold the ring and gasket down, be extremely careful. The screws rust and will break off. Then you might as well buy a new fuel tank and start all over.
However, you can just get a pressure test run on the fuel tank first and try that route before taking anything apart. Also, if you look under the panel at the fuel pump connection/hoses. Check the hoses really closely... a pin hole is enough to cause a vaccuum leak to cause the engine light to come on.
Another thing you might want to try... disconnect your battery for approximately 30 minutes and then reconnect it. After your ECU resets your "Check Engine" light might stay off.
Hope this info helps. Let me know.
Vanessa

We have done everything we can think of. We've had the diagnostic check run & no codes are showing up. The only thing the manual says is that it's an emmisions problem. The gas cap is tight. Any ideas?