What would keep a car from starting after short drives and then start after waiting 30 minutes?

Answer 1

First does the motor turn over but not fire ?If yes then there are a few possibilities: an injector could be leaking. When the engine is turned off, the fuel that is pressurized in the fuel line could be leaking into the throttle body or intake manifold (whichever yours has) and flooding the engine. If that's the case, the only solution is to have the injector cleaned or replaced or possibly a little injector cleaner through the next tank MAY make a difference, but don't count on it.

If the motor does not turn over (will not crank ) the second possibility, overheated component. Many electrical components heat up when they are in use and if there are transistors or other electronic parts that fail when hot, the component may run fine while cool and while air is flowing but once it warms up the component fails. The list could include the fuel pump, relay or ignition components. If the starter is covered in oil ( how almost every starter fails ) it is probably your problem . Also old distributor caps and rotors can run fine (from a cold start) but not start once hot .