2006 Sonata 4cyl cranks but won't start

I have a 2006 Sonata 4cyl with A/T
I have owned the vehicle for three years and currently has 205,000 miles on it. The situation has only happened 3-4 times since I've owned it. Occasionally
after the car has warmed up and has been running a while,it will crank but will not start.
The episode lasts about 3-5 minutes, and once it starts, it runs fine. Sometimes when it cranks it acts like it wants to start,and sometimes it cranks and there's nothing at all.
The no-starts have been very sporadic, however the last two episodes occurred a week apart and the last episode lasted over an hour before the car would start.
The check engine light did come on for a few days during this time,but has since gone out. I'm not sure if it's related.I plan to have a diagnostic check done next week.
I also recently experienced a loud rattle on start up, which I understand may indicate a failing timing chain tensioner. I've been looking at a lot of forums with people having similar problems, and many suspected reasons center around the crankshaft and camshaft position sensors. I'm now wondering if the problem may be related to the engine management system and apparent timing components wear.
I want to have the job done right, but I'm afraid of the repair shop throwing a bunch of parts at the car trying to solve the problem. Any help anyone can share narrowing down the problem would be appreciated.
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The trouble code stored from the check engine lamp is a good place to start . Check for stored codes sooner rather than later. If too long a period p asses, the computer may erase the code on its own.
Realistically, there are a large number of possibilities, and without some sort of evidence such as a stored diagnostic trouble code, your ability to find this will probably depend on doing tests while the condition is occurr ing.
A faulty fuel pump is the most common cause for a crank-no start condition on this vehicle. This is not typically intermittent, however, and usually does not cause a check engine lamp to illuminate.
Number two would be a faulty crank sensor. To my knowledge, a faulty cam s ensor will not cause the engine to not start.
In regard to the rattling, the timing chain tensioner issue was a known pro blem only on the V6 engine, not the four cylinder. That doesn't mean this isn't an issue, but the fact I've never seen nor heard of this issue on the four cylinder engine means it's unlikely. I wonder if one of your catalyt ic converters has broken apart and is rattling. If the broken piece were t o lodge in the exhaust and block it, that would explain both the rattling a nd the no-start condition. If you have a catalyst efficiency code, you sho uld suspect a broken catalyst is the reason for the rattling and no-start.
Realistically, there are too many options to review them all. Anything I h aven't mentioned here is relatively rare. If you want, report back with th e trouble code and I'll tell you what I think.
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