Problem with car start after a long drive

You may have a problem with a blockage in the intake tract or exhaust tract. There could also be a fuel management issue.
I am giving you a walk through diagnostic for this situation. It goes over all of the most probablble causes and how to recognize them and test and also fix them in some of the walk throughs. It goes into more detail on each possibility than I can hear. It is very well put together.

Here is the link;

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

There is not much else I can think of to go on as far as diagnosis at this point. The big problem is that it is intermitant and something is degrading slowly and cannot be replicated all teh time. You almost have to wait for whatever is wrong to get worse before you can find out what is wrong. If the trouble codes have been checked that means nothing is ouside of the specs far enoguh to be an issue. However, something is going outside of spec at some point while you are having the issue.
If I have not sugggested testing the fuel pressure, that is something you shoudl do and believe it is covered in the wlak through I gave you. The only poroblem is that it would be best to check it when you are having the issue. You might test it and it is fine when the issue is not present but it might be out of psec when the car won't start.
If you are under a warranty the most impoatant thing is to have the issue documented. Also make sure you get a copy of the documentation. This should be something that goes into the dealership database that Hyundai could acess later if needed. You will want some kind of printout that is liek a repair order or smething that shows the data was put into a database and reported at some point. Also, try and go to another dealer and have them try to diagnose it and have it documented there as well. Once warranty runs out and the issue returns and fails completely so replication is no loonger an issue, you will have a good chance at geting it fixed for free or at least at a discount. This will depend on how many times and places you report it and document it and how long after the warranty experation the problem is bad enoguh that the vehicle does not work at all.
Otherwise the issue will be all on your dime even thoguht warranty should cover it as it is a problem and if you are under waranty you have the right to have it fixed even though it could not be diagnosed at the time.

If you need anything else, let me knwo.
We are always here for any issue that pops up. So come back anytime you need halp or advice.

Take care and let me know how it turns out.

Dr. C

You are very welcome. Come back any time if you have any other problems or need advice. We are always here to help.

It is probably something electrical that is failing slowly and intermitantly. I don't think they ever got back to me with an answer on what the fuel pressure was, but that would be the first thing I would test.