My 2006 kia sportage lost power while driving. It has fuel and spark. The engine cranks but won't turn over. cylinders show no compression and the only trouble code is for crank position sensor.

You are going past the required change interval on the belt. If the engine is an interference type engine then you may have a piston and valve collision and it is a replacement issue

Back to basics, then, with checking for gas and spark. Sudden no-starts are usually caused because either gas or spark has been lost. Check fuel pressure with a fuel pressure gauge, and check for spark at a spark plug wire.
Fuel pressure should be within specs-it is pretty high for multi-port injection, about 50 psi, but Kia would have specs. If you have no spark, need to diagnose the ignition system-plug wires, coils, ignition control modules, crank sensor, ecu...

Caaarburetor? It's fuel injected, isn't it? Check the compression of your cylinders. If the timing is right, the engine just needs fuel, compression, and spark to start and run.

The engine can't run without compression in the cylinders. The plug will still spark, but without a compressed air/fuel mixture to burn and power the cylinder down, the starter will just keep spinning the engine over, cranking forever and not starting.
Check if your timing belts are good and not broke. Cylinder compression is dependent on good piston rings, intake and exhaust valves that open and close at right times and that seal good when closed, and a head gasket that seals up the cylinder from leaks where compression could blow into the water passages, or oil passages, or to outside of engine.
If the timing belts are good, a leak-down test of each cylinder will pinpoint where compression is lost.
Good luck with the Sube, great cars, great engines, but the head gaskets are a common problem.

contact the parts store for specs they should have it on the computer system under overhaul specs..ask for a printout of rebuild proceedures..

the next things i would check would be seeing if you have spark from the ignition system , compression in the cylinders by performing a compression test, and checking the timming belt to make sure it has not failed and come out of time.

It sounds like a head gasket issue. Do a compression check to see if all cylinders are within specs. If you find there is an issue, decide if it is worth the repair cost. If you choose to repair it you will also want to check for an exhaust leak close to the engine such as flex pipe and also back pressure from a plugged converter. Otherwise you could end up blowing the head gasket again.

When en engine won't start, there could be a number of things wrong. An engine requires air, fuel, and spark to start. You need to start by checking for spark. Take out one of the spark plugs and plug it back into the wire. Have somebody else turn the key while you hold the plug up to something metal on the engine, right next to the spark plug hole will be fine. You should see a bright blue spark, if you don't then you probably need to replace the spark plugs. You can do this same thing with any of the spark plugs. If you don't have spark on any of the plugs, get back with me and we'll go from there.

Hello mrhbollinger: My name is Roger and I will help you. You did not say Exactly what happened. If you were driving down the road and the engine died? Or if you pulled up to a stop and the engine died? I would check a few things first. Does the engine have over 60,000 to100,000 miles on it? If so I would look at the timing belt as a problem. Check the compression Compression should be around 160 psi. Any thing less then a 100 psi. the cylinder will not fire. Also keep in mind that this engine is a interference engine. This means should the timing belt break. The engine will suffer severe internal engine damage. By that I mean any valve that was open when timing belt broke will be damaged. Piston damage will also accrue. If the timing belt is not th problem I would look at the fuel system you should have 43 psi at the test port.I would also test for spark at the spark plug wires. If you have none and you check spark first. Check compression to make sure the timing belt is not the problem. If you remove the oil cap and can see the the camshaft. Have some one crank the engine over. If the valves do not move the timing belt is the problem. Should you need further help please just ask Thank You for using Fix Ya. Roger

If you have spark and fuel the next thing you have to have is compression, if you dont have compression your valve timeing is off,if your has a belt for the cam it broke,I hope this helps you?