How to Diagnose Problems If Your Car Won't Start
If your car won’t start and you left your lights on after you turned off the engine, your battery is dead. But your conventionally fueled vehicle may not start for a number of reasons. The following list outlines the most common circumstances and tells you what action you can take to try to remedy each situation:
The car is silent when you turn the key in the ignition: Check the battery terminal cable connections. If they look really corroded, you need to clean the battery posts and cable connectors or replace the cables and try to start the engine.
The car makes a clicking noise but won’t start: This sound usually means a dead battery. If not, check the wiring to and from the starter for a loose connection.
Be sure the ignition is off and the vehicle is in Neutral or Park before you raise the hood and remove the distributor cap.
If you find moisture, get some mechanic’s solvent from your friendly service station — they use it to clean car parts — or buy an aerosol can of it at an auto supply store. To evaporate any dampness inside the distributor cap, turn the cap upside down and pour or spray some solvent into it. Swish it around and pour it out. Then dry the cap as best you can with a clean, lint-free rag, and replace the cap.
Use only clean solvent; even a tiny speck of dirt can foul the points. Gasoline won’t do because a spark can ignite gasoline fumes and cause an explosion or a fire.
The car won’t start on cold mornings: If you have fuel injection, you need to have a professional diagnose the cold-start problems.