The fist thing to do is determine if the engine is cranking over or not. If it is not then it is most likely battery related. If it cranks over but does not start then it would be spark or fuel related in most cases. Make sure you have fuel in the tank. On some vehicles you can simple spray starting fluid in the air filter to see if it will start. If it does then most likely you are out of gas or the fuel pump has failed. Full Diagnostic Chart.