"03 Chrysler 300M Special -- Occasional Hard Start Issue

2003 Special with 96K has developed an intermittent hard start problem. Car has had recent tune up, new timing belt, and cam sensor placement sensor. The car drives fine but at times will not start. These hard starts usually occur after the initial start up. I may start the car, run an errand or drive for miles, leave the car for a few minutes, and the car won’t start. The engine turns over, but there is no firing of the motor – sounds flooded. The car will eventually start after repeated attempts and some waiting. I have tried fuel injector cleaner. There are no codes. Car is averaging the same MPG as always. Can someone help me diagnose this problem? Thanks!

The next time it won’t start, try a flood clearing start and see if it works (gas pedal floored while you turn the key). If that gets is going it probably is flooded.

That will most likely be a bad fuel pressure regulator or leaky fuel injector(s). Next time you park the car for one of those periods of time pull the vacuum hose from the pressure regulator & check for gas. If there is any, get a new regulator.

The other thing to do is carry around a spark tester - when it won’t start, check for spark as this kind of thing can also be ignition related.

For an engine to run, it must have spark, fuel, and air (in the right proportions). Tests for these needs to be done when the engine won’t start.
Your engine has an ignition coil on each spark plug (COP). To check one for spark, the “ignition coil on plug” (COP) would have to be removed, and a spark tester connected. There IS a tester which can be laid on top of the COP (and, the COP WOULDN’T need to be removed for tests), and it will indicate whether there is spark. It’s too expensive for most people ($85); but, it’s cheaper than some wildly changed parts.
Here’s several Spark Testers: http://www.toolfetch.com/spark-testers.shtml