Hyundia Elantra

Why won’t my car start when I turn key off and stay in car?

Say that again. Use big words, for clarity.

Because you are supposed to turn the key back on to start the car.

Your question is not real clear. I would guess you need to turn the car totally off and remove the key then put the key back in to restart it. It is also possible you may need to put the transmission into park.

Huh?

For clarity: I was stopped for a train and turned the ignition off, but left key in. After 10 min. or so tried to start. Nothing. Took it to dealer and they found nothing wrong after testing all day. Next time, when getting gas, same thing, forgot DUH. Left key in ignition, pumped gas, went for soda, tried to start. Nothing. It will start again after many minutes (5-20). Now this weekend, went to the bank, Niece called on cell phone so, forgot about key issue, turned car off, must have left key in (not sure). Again, wouldn’t start. This time took a long time before starting… What’s going on???

I do remove key, It is in park. Dead as a doornail, Will start again many minutes later. No problem found at dealer after looking all day. Happened once stopped at train, once getting gas, once at bank. Seems only if I sit in car with key in ignition. HMMM

What model year is your Hyundai Elantra. What alarm/anti-theft system does the the car have? If it has the system, is it original, from the factory?
When the ignition key has been left in, and you attempt to start, what happens? Does the engine crank (turn over)? If it turns over, does it sound like it turns at a good rate?
Is the key chipped (for the ignition I.D.)? Or, will a solid metal key, normally, start the car?

It is an "05, with whatever theft came with the car, but that is the direction I am thinking also. I don’t know if key is chipped, same, original on that as well. The engine does not crank, then when it finally lets you start again it’s like it has to get fuel back in the lines???

Is this automatic or stick shift? If it’s automatic, try putting the transmission in neutral and see if it starts then. This could be the neutral/park safety switch being out of adjustment. If this is a stick shift, make sure your foot is all the way down on the clutch. There is a clutch safety switch on stick shift cars.

I tried to make it clear that “crank” and “turn over” are exactly the same thing. Your answer isn’t clear. When you say, “…the engine does not crank”, do you mean that it does not turn over? If you don’t have a solid key key to try in the ignition switch, could you have a copy made at Walmart (wherever), and try it?
The Owner’s Handbook (look for it in the glove box) with tell you about the security/anti-theft system. Good reading!
If an engine does not crank (turn over), in a car with a security/anti-theft system, it likely that that system is preventing cranking (turning over). I can’t make this any clearer.

When the ignition key is turned to START, it powers the Bugler Alarm Relay which is grounded by the ETACS (or, ETACM) module. Then that voltage goes through some more switches to the starter relay.
If the engine doesn’t crank, it may be the Bugler Alarm Relay, or it may be the ETACS module (which energises that relay). Swap Bugler Alarm Relay with any other relay in the relay box. Usually, there are several relays which are of the same type in the relay box.

Some Hyundai from 1999 thru 2005 (including 2004 - 2005 Elantra), had fuel level sender resistors which did not match the “new instrument cluster”. The result is that the gas tank will indicate 1/4 tank; but, the tank is empty! This is explained in Hyundai Technical Service Bulletin TSB 04-30-003. There is no recall on this, just the TSB (kind of FYI to the dealer).