How to diagnose a no start problem.

Since most passenger cars run on gas this article pertains to gasoline engines. Even so, there are so many differences between models and makes that this article can only be used as a generic guide to help you find the trouble. Refer to a repair manual specific to your vehicle for exact procedures. Still, the following may aid you in identifying the problem.

The first thing to do is make sure the engine turns over. If it does not, the starter circuit must be repaired. Check the battery, wiring connections and the starter itself. Replace or repair as necessary.

No matter how new or old it is an engine needs three things to fire. Compression, correct fuel mixture and a spark at the right time to ignite it. If any of these three are missing it will not start.

Look for a spark first. Remove a plug wire and insert a philips screwdriver into it. Hold the shaft of the screwdriver about one quarter inch away from a metal engine part. Crank the engine and look for a spark to jump between the two. If there is no spark make a thorough check of the ignition system. Check the rotor, distributor cap, electronic ignition module, coil and coil wire for any problems. The spark timing is also important. Follow the instructions for ignition timing for your specific vehicle.

If there is a spark, check for correct fuel mixture. An engine with too much fuel usually will fire but not keep running. If it won't fire at all, its probably not getting any gas. Test this theory by removing whatever parts are necessary to get to the carburetor or intake manifold. Pour a thimble full of gas in the manifold and crank the engine. If it fires a few times and stops the trouble is the fuel supply. Make sure there is gas in the tank. Then check fuel pump, carburetor, fuel injection system, etc. for too little or too much fuel.

If there is a spark and gas, check for compression. To do this you will need a compression tester available at an automotive shop. Follow the testers instructions for a compression test. If this is the trouble the engine will probably need serious repair. The internal parts are worn out and therefore cannot form a strong enough seal to compress the fuel air mixture. It might be time for some car shopping.

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