I have a 2005 V6 Hyundai Sonata. Whenever I fill the gas tank to half or above, when I try to start it, it stalls. It never does this if I fill to less than half. To get it to stop I have to press the gas pedal a few times and eventually it will stay running. It usually takes about 3 to 4 attempts each time. Once I’ve got it started the problem doesn’t return until the next fill up. Does anyone know what could be causing this? I’ve talked to a couple different mechanics and they couldn’t tell me anything.
The purge valve in the EVAP system is probably leaking.
When this happens, fuel vapors are forced into the engine as you refuel the vehicle causing a flooded condition where the engine is hard to start and runs rough when it does start.
To verify this, the next time you refuel the vehicle, hold the gas pedal to the floor when you go to start the engine.
If the engine starts right up and runs normally that’s what’s happening.
And, after the Purge Valve is replaced, the OP should resolve to never again fill the tank after the pump clicks off for the first time.