I have a Kia Rio 2004, I can't start it. It

check fuses for fuel pump and ignition. You need to determine whether you are getting spark to your sparkplugs, then fuel. When you turn your key on , you should hear the fuel pump humm for a couple of seconds, to build up fuel pressure. If you don't hear it, suspect fuel problem.

2003 kia have spark on one coil but not the other 2.4 lit.and i know both coils are good?

I had a similar problem with my car Rio not starting. It was NOT a serious problem. It turns out the diagnostic system sensed the gas cap wasn't on tight enough.

The solution was to tighten the gas cap AND diconnect the positive battery cable for a few seconds and then reconnect. This resets the diagnostic system which senses the correct pressure and then allows you car to start.

Ridiculous but true.

There are several things that can cause this. Worse case scenario, the timing belt broke and you are going to have one heck of a time getting everything repaired. Before you go pulling the fuel pump and everything, check your fuses, on the engine valve cover there may be a small circlular rubber plug you can remove, remove this and while looking at the hole have some one turn the engine over. If, while the engine is turning, you don't see the sprocket that is visible once you remove the plug turning STOP. The timing belt has broken. You will need to rebuild the engine at least partially and depending on what kind of damage was done may have to remove the cylinder head and have it repaired as well. Another step to verify is to do a compression check on the motor and see if you have compression on all cylinders. No compression after a situation like this can also indicate a broken timing belt. Unlike most v-6 motors the typical 4 cylinder uses a belt instead of a chain and is only really visible after partial disassembly. With the electronic coil pack you can no longer just look at the Distributor to see if it turns.