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George H.
George H., Hyundai Technician
Category: Hyundai
Satisfied Customers: 18308
Experience:  Hyundai Gold certified, ASE Master tech 15+ years
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Hyundai Sonata GL: I have a 2004 Haundai Sonata that wont turn

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I have a 2004 Haundai Sonata that wont turn over when I fill the tank full. It takes a few times of turning over but eventually starts and goes back to normal. What could be wrong??

Hello I will help you with your question,

This is usually a problem with the evaporative emission system and the charcoal canister and purge valve.

The canister will come apart and leak charcoal into the system which sticks the purge valve open. When you fuel the tank the fumes and maybe some liquid fuel is forced into the engine flooding it until you crank it for a few seconds/minutes. Holding the throttle pedal to the floor will usually allow the engine to start.

Is the check engine light on?

Let me know so I can help

Thank you

Customer: replied 3 years ago.

no the check engine light is not on...I recently purchased this car and it is in great condition. I guess i didnt check to see if the owner didnt reset the computer first...ugh!


Good, if you just got it try not to fill the tank too full. When the pump clicks off stop filling.

Next time you do fill it try just pushing the pedal t the floor then crank th engine with the starter. If it starts right away you know what is happening.

The canister and purge valve are about $150 and the labor to install them after blowing out the lines is about the same so $300. If the check engine light comes on with small leak codes for the Evaporative emission system in the next couple of weeks then you will know what is happening and what needs to be done.

Please let me know how I Can help

Thank you

Customer: replied 3 years ago.

ok , if i just fill it up without going full will my car start normally or is this a problem whenever i put any amount of gas? AND


so i push down the throttle then turn over right? And it should just start up normally?



When you are filling the tank the vapors need some place to go to make room for the liquid fuel you are adding to the tank. This will push the vapors into the engine if the valve up there is stuck open. There is another valve that is supposed to let the vapor out through the charcoal canister but when it comes apart it clogs so the vapors cannot get out that way.

You may be able to start it normally (no pushing on the throttle at all) if you only put a couple of gallons in but when you fill it then you have the problem. You push the pedal to the floor and turn the key, this is called "clear flood" mode and will shut off the fuel injectors so only the vapors that were pushed into the engine will be available to be burned. If it starts normally then you know what is happening.

If it does not start right away with your foot on the floor then release the pedal, turn off the key and try again without pressing the pedal.

Let m e know how I can help you with this

Thank you

Customer: replied 3 years ago.

Can this problem get worse if i dont replace the parts you mentioned or can i just follow your steps and drive my car normally?

Yes, it will get to the point that the pump will click off every few cents as you try to fill the tank and it can lead to stalling of the engine. Best to drive it for the next couple of weeks and see if you get a check engine light and if you do then replace the purge valve and canister after having the system blown clean of charcoal.

Let me know how I can help

Thank you

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